Sacrum
/ˈseɪkrəm/
A triangular bone in the lower back formed from fused vertebrae and situated between the two hip bones.
Sagittal plane
/ˈsædʒɪtəl pleɪn/
An anatomical plane that divides the body into right and left parts.
Saline
/ˈseɪliːn/
A solution of salt (sodium chloride) in water.
Salivary glands
/ˈsælɪvɛri ɡlændz/
Glands that discharge a fluid secretion (saliva) into the mouth cavity.
Salmonella
/ˌsælməˈnɛlə/
A genus of bacteria that causes food poisoning, typhoid fever, and other diseases.
Salpingitis
/ˌsælpɪnˈdʒaɪtɪs/
Inflammation of the fallopian tubes.
Sanguineous
/sæŋˈɡwɪniəs/
Relating to blood; bloody.
Saphenous vein
/səˈfiːnəs veɪn/
One of the two main superficial veins of the leg.
Sarcoma
/sɑːrˈkoʊmə/
A malignant tumor of connective or other non-epithelial tissue.
Saturated fat
/ˈsætʃəreɪtɪd fæt/
A type of fat in which the fatty acid chains have all or predominantly single bonds.
Scabies
/ˈskeɪbiːz/
A contagious skin disease marked by itching and small raised red spots, caused by the itch mite.
Scalpel
/ˈskælpəl/
A small and extremely sharp bladed instrument used for surgery.
Scaphoid
/ˈskæfɔɪd/
A large carpal bone of the wrist articulated with the radius.
Scapula
/ˈskæpjʊlə/
The shoulder blade.
Scar
/skɑːr/
A mark left on the skin or within body tissue where a wound, burn, or sore has not healed completely and fibrous connective tissue has developed.
Sciatica
/saɪˈætɪkə/
Pain affecting the back, hip, and outer side of the leg, caused by compression of a spinal nerve root in the lower back.
Sclera
/ˈsklɪərə/
The white outer layer of the eyeball.
Scleroderma
/ˌsklɪərəˈdɜːrmə/
A chronic hardening and contraction of the skin and connective tissue.
Sclerosis
/skləˈroʊsɪs/
Abnormal hardening of body tissue.
Scoliosis
/ˌskoʊliˈoʊsɪs/
Abnormal lateral curvature of the spine.
Scrotum
/ˈskroʊtəm/
The pouch of skin containing the testicles.
Scurvy
/ˈskɜːrvi/
A disease caused by a severe deficiency of vitamin C, characterized by swollen bleeding gums and the opening of previously healed wounds.
Sebaceous gland
/sɪˈbeɪʃəs ɡlænd/
A small gland in the skin which secretes a lubricating oily matter (sebum) into the hair follicles.
Seborrhea
/ˌsɛbəˈriːə/
Excessive discharge of sebum from the sebaceous glands.
Sebum
/ˈsiːbəm/
An oily secretion of the sebaceous glands.
Secondary infection
/ˈsɛkəndɛri ɪnˈfɛkʃən/
An infection that occurs during or after treatment for another infection.
Secretion
/sɪˈkriːʃən/
A process by which substances are produced and discharged from a cell, gland, or organ.
Sedative
/ˈsɛdətɪv/
A drug taken for its calming or sleep-inducing effect.
Sedimentation rate
/ˌsɛdɪmɛnˈteɪʃən reɪt/
ESR; a blood test that can reveal inflammatory activity in your body.
Seizure
/ˈsiːʒər/
A sudden, uncontrolled electrical disturbance in the brain.
Semen
/ˈsiːmən/
The male reproductive fluid, containing spermatozoa in suspension.
Semicircular canals
/ˌsɛmiˈsɜːrkjʊlər kəˈnælz/
Three fluid-filled bony channels in the inner ear that help maintain balance.
Seminal vesicle
/ˈsɛmɪnəl ˈvɛsɪkəl/
Each of a pair of glands that open into the vas deferens and secrete many of the components of semen.
Senescence
/sɪˈnɛsəns/
The condition or process of deterioration with age.
Senile
/ˈsiːnaɪl/
Having or showing the weaknesses or diseases of old age, especially a loss of mental faculties.
Sensation
/sɛnˈseɪʃən/
A physical feeling or perception resulting from something that happens to or comes into contact with the body.
Sepsis
/ˈsɛpsɪs/
A life-threatening complication of an infection.
Septicemia
/ˌsɛptɪˈsiːmiə/
Blood poisoning, especially that caused by bacteria or their toxins.
Septum
/ˈsɛptəm/
A partition separating two chambers (e.g., in the nose or heart).
Sequela
/sɪˈkwɛlə/
A condition which is the consequence of a previous disease or injury.
Serology
/sɪˈrɒlədʒi/
The scientific study or diagnostic examination of blood serum.
Serosa
/sɪˈroʊsə/
The tissue of a serous membrane.
Serum
/ˈsɪərəm/
An amber-colored, protein-rich liquid that separates out when blood coagulates.
Sesamoid bone
/ˈsɛsəmɔɪd boʊn/
A small independent bone or bony nodule developed in a tendon (e.g., the patella).
Shingles
/ˈʃɪŋɡəlz/
Herpes zoster; a painful, blistering skin rash caused by the varicella-zoster virus.
Shock
/ʃɒk/
A critical condition brought on by the sudden drop in blood flow through the body.
Shoulder blade
/ˈʃoʊldər bleɪd/
The common name for the scapula.
Shunt
/ʃʌnt/
An act of pushing or pulling something to one side; in medicine, a hole or passage which moves, or allows movement of, fluid from one part of the body to another.
Sialogram
/saɪˈæləˌɡræm/
An X-ray of the salivary ducts and glands.
Sickle cell anemia
/ˈsɪkəl sɛl əˈniːmiə/
A severe hereditary form of anemia in which a mutated form of hemoglobin distorts the red blood cells into a crescent shape.
Side effect
/saɪd ɪˈfɛkt/
A secondary, typically undesirable effect of a drug or medical treatment.
SIDS
/sɪdz/
Sudden Infant Death Syndrome; the unexplained death of a seemingly healthy baby less than a year old.
Sigmoid colon
/ˈsɪɡmɔɪd ˈkoʊlən/
The S-shaped last part of the large intestine, leading into the rectum.
Sigmoidoscopy
/ˌsɪɡmɔɪˈdɒskəpi/
Examination of the sigmoid colon by means of a flexible tube inserted through the anus.
Sign
/saɪn/
An objective evidence of disease (something a doctor sees), as opposed to a symptom (something a patient feels).
Silicosis
/ˌsɪlɪˈkoʊsɪs/
Lung disease caused by inhaling silica dust.
Sinus
/ˈsaɪnəs/
A cavity within a bone or other tissue, especially one in the bones of the face or skull connecting with the nasal cavities.
Sinusitis
/ˌsaɪnəˈsaɪtɪs/
Inflammation of a nasal sinus.
Skeletal muscle
/ˈskɛlɪtəl ˈmʌsəl/
A muscle which is connected to the skeleton to form part of the mechanical system which moves the limbs and other parts of the body.
Skeleton
/ˈskɛlɪtən/
The internal framework of the body, composed of bone and cartilage.
Skin
/skɪn/
The thin layer of tissue forming the natural outer covering of the body of a person or animal.
Skin graft
/skɪn ɡræft/
A surgical operation in which a piece of healthy skin is transplanted to a new site on the body.
Skull
/skʌl/
The bony structure that forms the head in vertebrates.
Sleep apnea
/sliːp ˈæpniə/
A potentially serious sleep disorder in which breathing repeatedly stops and starts.
Sling
/slɪŋ/
A flexible strap or belt used in the form of a loop to support or raise a weight; in medicine, used to support an injured arm.
Slipped disc
/slɪpt dɪsk/
A common name for a prolapsed or herniated intervertebral disc.
Slough
/slʌf/
A layer or mass of dead tissue separated from surrounding living tissue, as in a wound or inflammation.
Small intestine
/smɔːl ɪnˈtɛstɪn/
The part of the intestine that runs between the stomach and the large intestine; consists of the duodenum, jejunum, and ileum.
Smallpox
/ˈsmɔːlpɒks/
An acute contagious viral disease, with fever and pustules usually leaving permanent scars; it was effectively eradicated worldwide by 1980.
Smear
/smɪər/
A sample of tissue or secretions spread on a glass slide for microscopic examination.
Smooth muscle
/smuːð ˈmʌsəl/
Involuntary muscle tissue in the walls of viscera and blood vessels, lacking the striated appearance of skeletal muscle.
Snellen chart
/ˈsnɛlən tʃɑːrt/
An eye chart used by eye care professionals to measure visual acuity.
Sodium
/ˈsoʊdiəm/
An essential electrolyte that helps maintain the balance of water in and around your cells.
Soft tissue
/sɒft ˈtɪʃuː/
Tissues that connect, support, or surround other structures and organs of the body (e.g., muscles, fat, blood vessels).
Solar plexus
/ˈsoʊlər ˈplɛksəs/
A complex of radiating nerves at the pit of the stomach.
Solute
/ˈsɒljuːt/
The minor component in a solution, dissolved in the solvent.
Somatic
/soʊˈmætɪk/
Relating to the body, especially as distinct from the mind.
Somnambulism
/sɒmˈnæmbjʊˌlɪzəm/
The medical term for sleepwalking.
Somnolence
/ˈsɒmnələns/
A state of strong desire for sleep, or sleeping for unusually long periods.
Sonogram
/ˈsɒnəˌɡræm/
A visual image produced from an ultrasound examination.
Soporific
/ˌsɒpəˈrɪfɪk/
Tending to induce sleep.
Spasm
/ˈspæzəm/
A sudden involuntary muscular contraction or convulsive movement.
Spasticity
/spæsˈtɪsɪti/
A condition in which certain muscles are continuously contracted, causing stiffness or tightness.
Speculum
/ˈspɛkjʊləm/
A metal or plastic instrument used to widen an opening of the body to allow a doctor to look inside.
Sperm
/spɜːrm/
The male reproductive cell.
Spermicide
/ˈspɜːrmɪˌsaɪd/
A substance that kills spermatozoa, used as a contraceptive.
Sphincter
/ˈsfɪŋktər/
A ring of muscle surrounding and serving to guard or close an opening or tube (e.g., the anus or the exit of the stomach).
Sphygmomanometer
/ˌsfɪɡmoʊməˈnɒmɪtər/
An instrument for measuring blood pressure, typically consisting of an inflatable rubber cuff.
Spina bifida
/ˌspaɪnə ˈbɪfɪdə/
A congenital defect of the spine in which part of the spinal cord and its meninges are exposed through a gap in the backbone.
Spinal cord
/ˈspaɪnəl kɔːrd/
The cylindrical bundle of nerve fibers and associated tissue which is enclosed in the spine and connects nearly all parts of the body to the brain.
Spine
/spaɪn/
The series of vertebrae extending from the skull to the small of the back, enclosing the spinal cord.
Spirochete
/ˈspaɪrəˌkiːt/
A flexible spirally twisted bacterium, especially the one that causes syphilis.
Spirometer
/spaɪˈrɒmɪtər/
An instrument for measuring the air capacity of the lungs.
Spleen
/spliːn/
An abdominal organ involved in the production and removal of blood cells and forming part of the immune system.
Splenectomy
/splɪˈnɛktəmi/
Surgical removal of the spleen.
Splenomegaly
/ˌsplɛnəˈmɛɡəli/
Abnormal enlargement of the spleen.
Splint
/splɪnt/
A rigid or flexible device used to keep in place and protect an injured part of the body.
Spondylitis
/ˌspɒndɪˈlaɪtɪs/
Inflammation of the joints of the backbone.
Spondylosis
/ˌspɒndɪˈloʊsɪs/
A painful condition of the spine resulting from the degeneration of the intervertebral discs.
Sprain
/spreɪn/
Wrench or twist the ligaments of a joint violently so as to cause pain and swelling but not dislocation.
Sputum
/ˈspjuːtəm/
A mixture of saliva and mucus coughed up from the respiratory tract.
Squamous cell
/ˈskweɪməs sɛl/
Thin, flat cells that look like fish scales, found in the tissue that forms the surface of the skin.
Staging
/ˈsteɪdʒɪŋ/
A way of describing the size of a cancer and how far it has spread.
Stapes
/ˈsteɪpiːz/
The stirrup-shaped small bone in the middle ear.
Staphylococcus
/ˌstæfɪləˈkɒkəs/
A bacterium of a genus that includes many pathogenic kinds that cause pus formation, especially in the skin and mucous membranes.
Stasis
/ˈsteɪsɪs/
A period or state of inactivity or equilibrium; in medicine, the stopping of the normal flow of a body fluid.
Statin
/ˈstætɪn/
A class of lipid-lowering medications that reduce cholesterol levels.
Steatosis
/ˌstiːəˈtoʊsɪs/
Abnormal retention of lipids within a cell or organ, often the liver.
Stenosis
/stɪˈnoʊsɪs/
The abnormal narrowing of a passage in the body.
Stent
/stɛnt/
A tubular support placed temporarily inside a blood vessel, canal, or duct to aid healing or relieve an obstruction.
Stereopsis
/ˌstɛriˈɒpsɪs/
The perception of depth produced by the reception in the brain of visual stimuli from both eyes in combination.
Sterile
/ˈstɛraɪl/
Free from bacteria or other living microorganisms; also refers to being unable to produce offspring.
Sternum
/ˈstɜːrnəm/
The breastbone.
Steroid
/ˈstɛərɔɪd/
A large group of chemical substances, such as hormones and drugs, used to reduce inflammation and treat various conditions.
Stethoscope
/ˈstɛθəˌskoʊp/
A medical instrument for listening to the action of someone's heart or breathing.
Stimulant
/ˈstɪmjʊlənt/
A substance that raises levels of physiological or nervous activity in the body.
Stimulus
/ˈstɪmjʊləs/
A thing or event that evokes a specific functional reaction in an organ or tissue.
Stitch
/stɪtʃ/
A loop of thread or suture used to join the edges of a wound or surgical incision.
Stoma
/ˈstoʊmə/
An artificial opening made into a hollow organ, especially one on the surface of the body leading to the gut or trachea.
Stomach
/ˈstʌmək/
The internal organ in which the major part of the digestion of food occurs.
Stomatitis
/ˌstoʊməˈtaɪtɪs/
Inflammation of the mucous membrane of the mouth.
Stool
/stuːl/
Waste matter discharged from the bowels; feces.
Strabismus
/strəˈbɪzməs/
A condition in which the eyes do not properly align with each other when looking at an object; 'crossed eyes'.
Strain
/streɪn/
An injury to a muscle or tendon in which the muscle fibers tear as a result of overstretching.
Strangulation
/ˌstræŋɡjʊˈleɪʃən/
The compression of a part of the body, such as the bowel or a limb, that stops the flow of blood.
Stratum corneum
/ˈstrɑːtəm ˈkɔːrniəm/
The horny outer layer of the skin.
Streptococcus
/ˌstrɛptəˈkɒkəs/
A bacterium of a genus that includes those causing scarlet fever, tonsillitis, and pneumonia.
Stricture
/ˈstrɪktʃər/
An abnormal narrowing of a canal or passage in the body.
Stride
/straɪd/
The distance covered by one complete cycle of a person's gait; used in physical therapy assessment.
Stridor
/ˈstraɪdər/
A harsh or grating sound in inhalation, caused by obstruction of the windpipe or larynx.
Stroke
/stroʊk/
A sudden disabling attack or loss of consciousness caused by an interruption in the blood supply to the brain.
Stroma
/ˈstroʊmə/
The supportive framework of a biological cell, tissue, or organ.
Stupor
/ˈstuːpər/
A state of near-unconsciousness or insensibility.
Sty
/staɪ/
Hordeolum; a red, painful lump near the edge of the eyelid that may look like a boil or a pimple.
Subacute
/ˌsʌbəˈkjuːt/
Between acute and chronic; a stage of disease that is not quite sudden but not long-term.
Subarachnoid space
/ˌsʌbəˈræknɔɪd/
The space between the arachnoid membrane and the pia mater through which cerebrospinal fluid circulates.
Subclavian artery
/sʌbˈkleɪviən ˈɑːrtəri/
A major artery located below the clavicle that supplies blood to the arms.
Subclinical
/ˌsʌbˈklɪnɪkəl/
Relating to a disease which is not severe enough to present definite symptoms or signs.
Subcutaneous
/ˌsʌbkjuːˈteɪniəs/
Situated or applied under the skin.
Subdural hematoma
/sʌbˈdjʊərəl ˌhiːməˈtoʊmə/
A pool of blood between the brain and its outermost covering.
Subjective
/səbˈdʒɛktɪv/
Based on or influenced by personal feelings or opinions; in medicine, refers to symptoms reported by the patient.
Sublingual
/sʌbˈlɪŋɡwəl/
Applied under the tongue.
Subluxation
/ˌsʌblʌkˈseɪʃən/
A partial dislocation of a joint.
Submucosa
/ˌsʌbmjuːˈkoʊsə/
The layer of connective tissue beneath a mucous membrane.
Subphrenic
/sʌbˈfrɛnɪk/
Situated below the diaphragm.
Substance abuse
/ˈsʌbstəns əˈbjuːs/
Overindulgence in or dependence on an addictive substance, especially alcohol or drugs.
Substrate
/ˈsʌbstreɪt/
A substance on which an enzyme acts.
Succussion
/səˈkʌʃən/
The action of shaking the body to detect the presence of fluid and gas in a body cavity.
Sudoriferous gland
/ˌsuːdəˈrɪfərəs ɡlænd/
A sweat gland.
Suffocation
/ˌsʌfəˈkeɪʃən/
The state or process of dying from being deprived of air or unable to breathe.
Sulcus
/ˈsʌlkəs/
A groove or furrow, especially one on the surface of the brain.
Superego
/ˌsuːpərˈiːɡoʊ/
The part of a person's mind that acts as a self-critical conscience, reflecting social standards learned from parents and teachers.
Superficial
/ˌsuːpərˈfɪʃəl/
On the surface; not deep.
Superior
/suːˈpɪəriər/
Further above; higher in position.
Supination
/ˌsuːpɪˈneɪʃən/
Rotation of the forearm and hand so that the palm faces forward or upward.
Supine
/suːˈpaɪn/
Lying face upward.
Suppository
/səˈpɒzɪtəri/
A solid medical preparation designed to be inserted into the rectum or vagina to dissolve.
Suppuration
/ˌsʌpjʊˈreɪʃən/
The formation or discharge of pus.
Suprarenal
/ˌsuːprəˈriːnəl/
Situated above the kidney; relating to the adrenal glands.
Surfactant
/sɜːrˈfæktənt/
A substance which tends to reduce the surface tension of a liquid in which it is dissolved; in the lungs, it prevents the collapse of alveoli.
Surgeon
/ˈsɜːrdʒən/
A medical practitioner qualified to practice surgery.
Surgery
/ˈsɜːrdʒəri/
The branch of medicine that employs operative manual and instrumental techniques to treat pathological conditions.
Susceptibility
/səˌsɛptəˈbɪləti/
The state or fact of being likely or liable to be influenced or harmed by a particular thing.
Suture
/ˈsuːtʃər/
A stitch or row of stitches holding together the edges of a wound or surgical incision; also the immovable junction between bones of the skull.
Sympathetic Nervous System
/ˌsɪmpəˈθɛtɪk/
Part of the autonomic nervous system that prepares the body for 'fight or flight' responses.
Symphysis
/ˈsɪmfɪsɪs/
A place where two bones are closely joined, either forming an immovable joint or completely fused.
Symptom
/ˈsɪmptəm/
A physical or mental feature which is regarded as indicating a condition of disease, particularly such a feature that is apparent to the patient.
Symptomatic
/ˌsɪmptəˈmætɪk/
Serving as a symptom or sign, especially of something undesirable.
Synalgia
/sɪˈnældʒə/
Another term for referred pain.
Synapse
/ˈsaɪnæps/
A junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.
Synarthrosis
/ˌsɪnɑːrˈθroʊsɪs/
An immovably fixed joint between bones connected by fibrous tissue (e.g., the sutures of the skull).
Synchondrosis
/ˌsɪnkɒnˈdroʊsɪs/
A type of joint where the bones are joined by hyaline cartilage.
Synchronous
/ˈsɪŋkrənəs/
Existing or occurring at the same time.
Synclitism
/ˈsɪnklɪˌtɪzəm/
In obstetrics, the position of the fetal head when its sagittal suture is midway between the pubic symphysis and the sacral promontory.
Syncope
/ˈsɪŋkəpi/
Temporary loss of consciousness caused by a fall in blood pressure; fainting.
Syndactyly
/sɪnˈdæktɪli/
A condition where two or more digits are fused together; webbed fingers or toes.
Syndesmosis
/ˌsɪndɛzˈmoʊsɪs/
An immovable joint in which bones are joined by connective tissue (e.g., between the fibula and tibia at the ankle).
Syndrome
/ˈsɪndroʊm/
A group of symptoms which consistently occur together, or a condition characterized by a set of associated symptoms.
Syndromic
/sɪnˈdrɒmɪk/
Relating to or characteristic of a particular syndrome.
Synechia
/sɪˈnɛkiə/
A condition where the iris adheres to either the cornea or the lens of the eye.
Synergistic
/ˌsɪnərˈdʒɪstɪk/
Relating to the interaction or cooperation of two or more agents to produce a combined effect greater than the sum of their separate effects.
Syngeneic
/ˌsɪndʒəˈneɪɪk/
Genetically identical; used of individuals or tissues.
Synophthalmia
/ˌsɪnɒfˈθælmiə/
Cyclopia; a rare congenital disorder where the two orbits of the eye are fused into one.
Synosteosis
/ˌsɪnɒstiˈoʊsɪs/
The abnormal union of two neighboring bones by bony tissue.
Synovial fluid
/saɪˈnoʊviəl ˈfluːɪd/
A transparent, viscid lubricating fluid secreted by a membrane of a joint or tendon sheath.
Synovial membrane
/saɪˈnoʊviəl ˈmɛmbreɪn/
The connective tissue membrane that lines the cavity of a synovial joint and produces synovial fluid.
Synovioanalysis
/ˌsɪnoʊvioʊəˈnælɪsɪs/
Laboratory examination of synovial fluid to diagnose joint disease.
Synoviosarcoma
/ˌsɪnoʊviˌoʊsɑːrˈkoʊmə/
A malignant tumor arising from synovial tissue.
Synovitis
/ˌsɪnəˈvaɪtɪs/
Inflammation of a synovial membrane.
Synthesis
/ˈsɪnθəsɪs/
The production of chemical compounds by reaction from simpler materials.
Syntrophy
/ˈsɪntrəfi/
Biological interaction where the growth of one organism depends on the nutrients or factors provided by a neighboring organism.
Syphilis
/ˈsɪfɪlɪs/
A chronic bacterial disease that is contracted chiefly by infection during sexual intercourse.
Syringectomy
/ˌsɪrɪnˈdʒɛktəmi/
Surgical excision of the walls of a fistula.
Syringitis
/ˌsɪrɪnˈdʒaɪtɪs/
Inflammation of the Eustachian tube.
Syringomyelia
/sɪˌrɪŋɡoʊmaɪˈiːliə/
A chronic progressive disease in which longitudinal cavities form in the cervical segment of the spinal cord.
Systemic
/sɪˈstɛmɪk/
Relating to a system, especially as opposed to a particular part; affecting the whole body.
Systemic circulation
/sɪˈstɛmɪk ˌsɜːrkjʊˈleɪʃən/
The part of the cardiovascular system which carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart.
Systemic Lupus Erythematosus
/sɪˈstɛmɪk ˈluːpəs ˌɛrɪθiːməˈtoʊsəs/
SLE; an autoimmune disease in which the immune system attacks its own tissues, causing widespread inflammation and tissue damage.
Systole
/ˈsɪstəli/
The phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries.
Systolic pressure
/sɪˈstɒlɪk ˈprɛʃər/
The blood pressure when the heart is contracting; the first number in a blood pressure reading.