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Medical Dictionary


semiosis, semeiosis (se-me-o′sis)
The mental or symbolic process in which something ( e.g., word, symbol, nonverbal cue) functions as a sign for the organism. [G. semeiosis, fr. semeion, sign]

semiotic, semeiotic (se-me-ot′ik, sem-e-)
1. Relating to semiotics. 2. Relating to signs, linguistic or bodily. [G. semeiotikos, fr. semeion, sign]

semiotics, semeiotics (se-me-ot′iks, sem-e-)
1. The general philosophic theory of signs and symbols in communication, having three branches: syntactics, semantics, and pragmatics. 2. Obsolete term for symptomatology. [see semiotic]

semipennate (sem′e-pen′at) [TA]
1. Having a feather arrangement on one side; resembling one-half of a feather. 2. Denoting certain muscles with fibers running at an acute angle from one side of a tendon. SYN: unipennate&star, demipenniform.

semipenniform (sem′e-pen′i-form)
Penniform on one side. See semipennate muscle.

semipermeable (sem-e-per′me-a-bl)
Freely permeable to water (or other solvent) but relatively impermeable to solutes. Depending on the context, it has been used to imply impermeability to all solutes except very small uncharged molecules ( e.g., a cell membrane), or merely impermeability to very large molecules such as proteins ( e.g., a capillary membrane).

semipronation (sem′e-pro-na′shun)
The attitude or assumption of a partly prone position, as in Sims position.

semiprone (sem-e-pron′)
Denoting semipronation.

semiquinone (sem-e-kwin′on)
A free radical resulting from the removal of one hydrogen atom with its electron during the process of dehydrogenation of a hydroquinone to quinone or similar compound ( e.g., flavin mononucleotide).

semispinal (sem-e-spi′nal)
Half spinal; denoting muscles attached in part to the spinous processes of the vertebrae.

Semisulcospina (sem′e-sul-ko-spi′na)
A genus of operculate snails (family Pleuroceriidae, subclass Prosobranchiata). An oriental form, S. libertina, is the first intermediate host of a number of trematodes, including Paragonimus westermani. [semi- + L. sulcus, a furrow + spina, thorn, spine]

semisulcus (sem′e-sul′kus)
A slight groove on the edge of a bone or other structure, which, uniting with a similar groove on the corresponding adjoining structure, forms a complete sulcus.

semisupination (sem′e-soo-pi-na′shun)
The attitude or assumption of a partly supine position.

semisupine (sem-e-soo-pin′)
Denoting semisupination.

semisynthetic (sem′e-sin-thet′ik)
Describing the process of synthesizing a particular chemical utilizing a naturally occurring chemical as a starting material, thus obviating part of a total synthesis; e.g., the conversion of cholesterol (obtained from a natural source) into a corticosteroid.

semisystematic name (sem′e-sis-te-mat′ik)
A name of a chemical of which at least one part is systematic and at least one part is not ( i.e., is trivial). For example, calciferol includes the -ol suffix denoting an &cbond;OH radical, while calcifer-, which has no systematic meaning, is used only in this word. Cortisone contains the -one suffix, indicating a ketone group, but the rest of the term derives from cortex (adrenal). Hippuric acid (trivial) may be defined as N-benzoylglycine (semitrivial name); benzoyl is systematic for the C6H5–CO– radical, whereas glycine is the trivial name for α-aminoacetic (or 2-aminoethanoic, to be completely systematic) acid, and the N signifies that the benzoyl is attached to the nitrogen of glycine; from this, the structure C6H5–CO–NH–CH2–COOH is uniquely defined. Many generic or nonproprietary names of drugs, including USAN names, hormones, etc., are semitrivial in this chemical sense, although often termed trivial names; distinction between trivial and semitrivial is not often made. SYN: semitrivial name.

semitendinosus (sem′e-ten-di-no′sus)
SYN: semitendinous. [L.]

semitendinous (sem′e-ten′di-nus)
Composed in part of tendon; denoting the semitendinosus muscle. SYN: semitendinosus. [L. semitendinosus]

semitertian (sem-e-ter′she-an, -ter′shun)
Partly tertian, partly quotidian; denoting a malarial fever in which two paroxysms occur on one day and one on the succeeding day.

semitrivial name (sem-e-triv′e-al)
SYN: semisystematic name.

semivalent (sem-e-va′lent)
Denoting the ability to form a one-electron bond.

Richard W., German biologist, 1859–1918. See S.-Hering theory.

Sir David, English physician, 1856–1937. See S. vaccine.

semustine (se-mus′ten)
SYN: methyl-CCNU.

Francis E., U.S. dermatologist, 1889–1958. See S.-Usher disease, S.-Usher syndrome.

Senecio (se-ne′se-o, -she-o)
1. A large genus of plants (family Compositae), many species of which contain alkaloids that produce hepatic necrosis. 2. A common weed of the eastern U.S., formerly used in the treatment of amenorrhea and other menstrual irregularities. [L. a plant, groundsel, fr. s., an old man]

senecioic acid (se-ne′si-o-ik)
A polymer precursor and a precursor of isoprenoid and terpene compounds; the acid component of binapacryl in which it is esterified with 4,6-dinitro-2-(1-methylpropyl)phenol; the coenzyme A derivative is an intermediate in l-leucine degradation; used as a fungicide and miticide.

seneciosis (se-ne-se-o′sis)
Liver degeneration and necrosis caused by ingestion of plants of the genus Senecio, such as ragwort and groundsel; similar hepatotoxic properties have been observed after ingestion of some kinds of Crotalaria and Heliotropium.

senega (sen′e-ga)
The dried root of Polygala s. (family Polygalaceae), a herb of eastern and central North America; an expectorant. SYN: Seneca snakeroot. [Seneca, an Indian tribe]

senescence (se-nes′ens)
The state of being old. [L. senesco, to grow old, fr. senex, old] dental s. that condition of the teeth and associated structures in which there is deterioration due to normal or premature aging processes.

senescent (se-nes′ent)
Growing old.

Robert W., U.S. neurosurgeon, *1923. See S.-Blakemore tube.

senile (se′nil, sen′il)
Relating to or characteristic of old age. [L. senilis]

senility (se-nil′i-te)
Old age; a general term for a variety of organic disorders, both physical and mental, occurring in old age. [see senile]

senium (se′ne-um)
Rarely used term for old age; especially the debility of advanced age. [L. the feebleness of age, fr. seneo, to be old, feeble]

senna (sen′a)
The dried leaflets or legumes of Cassia acutifolia (Alexandrine s.) and C. angustifolia (Tinnevelly or Indian s.); a laxative. [Ar. sena]

sennoside A, sennoside B (sen′o-sid)
Two anthraquinone glucosides that are the laxative principles of senna.

sensate (sen′sat)
Able to perceive touch and other sensations; used in reference to patients who have had partial nerve or spinal cord injuries.

sensation (sen-sa′shun)
A feeling; the translation into consciousness of the effects of a stimulus exciting any of the organs of sense. [L. sensatio, perception, feeling, fr. sentio, to perceive, feel] delayed s. a s. that is not perceived until the lapse of an appreciable interval following the application of the stimulus. general s. a s. referred to the body as a whole rather than to any particular part. girdle s. SYN: zonesthesia. primary s. a s. that is the direct result of a stimulus. referred s. a s. felt in one place in response to a stimulus applied in another.

sense (sens)
The faculty of perceiving any stimulus. [L. sentio, pp. sensus, to feel, to perceive] chemical senses the senses of smell and taste. color s. the ability to perceive variations in hue, luminosity, and saturation of light. s. of equilibrium the s. that makes possible a normal physiologic posture. SYN: static s.. geometric s. one or other of two directions along a curve in which something is moving, e.g., clockwise or counterclockwise. joint s. SYN: articular sensibility. kinesthetic s. the sensation felt in muscle when it is contracting; awareness of movement or activity in muscles or joints; s. of position or movement mediated in large part by the posterior columns and medial lemniscus. SEE ALSO: bathyesthesia. SYN: deep sensibility, muscular s., myesthesia, myoesthesis, myoesthesia. light s. the ability to perceive variations in the degree of light or brightness. muscular s. SYN: kinesthetic s.. obstacle s. the ability, often found in the blind, to avoid objects without visual warning. position s. SYN: posture s.. posture s. the ability to recognize the position in which a limb is passively placed, with the eyes closed. SYN: position s.. pressure s. the faculty of discriminating various degrees of pressure on the surface. SYN: baresthesia, weight s.. seventh s. SYN: visceral s.. space s. the faculty of perceiving the relative positions of objects in the external world. special s. one of the five senses related respectively to the organs of sight, hearing, smell, taste, and touch. static s. SYN: s. of equilibrium. tactile s. SYN: touch (1) . temperature s. SYN: thermoesthesia. thermal s., thermic s. SYN: thermoesthesia. time s. the faculty by which the passage of time is appreciated. visceral s. the perception of the existence of the internal organs. SYN: seventh s., splanchnesthesia, splanchnesthetic sensibility. weight s. SYN: pressure s..

sensibility (sen-si-bil′i-te)
The consciousness of sensation; the capability of perceiving sensible stimuli. [L. sensibilitas] articular s. appreciation of sensation in joint surfaces. SYN: arthresthesia, joint sense. bone s. SYN: pallesthesia. cortical s. the integration of sensory stimuli by the cerebral cortex. deep s. SYN: bathyesthesia, kinesthetic sense. dissociation s. the loss of the pain and the thermal senses with preservation of tactile s. or vice versa. electromuscular s. s. of muscular tissue to stimulation by electricity. epicritic s. epicritic. pallesthetic s. SYN: pallesthesia. proprioceptive s. proprioceptive. protopathic s. protopathic. splanchnesthetic s. SYN: visceral sense. vibratory s. SYN: pallesthesia.

sensible (sen′si-bl)
1. Perceptible to the senses. 2. Capable of sensation. 3. SYN: sensitive. 4. Having reason or judgment; intelligent. [L. sensibilis, fr. sentio, to feel, perceive]

sensiferous (sen-sif′er-us)
Conducting a sensation. [L. sensus, sense, + fero, to carry]

sensigenous (sen-sij′e-nus)
Giving rise to sensation. [L. sensus, sense, + G. -gen, to produce]

sensimeter (sen-sim′e-ter)
An instrument that measures degrees of cutaneous sensation. [L. sensus, sense, + G. metron, measure]


sensitive (sen′si-tiv)
1. Capable of perceiving sensations. 2. Responding to a stimulus. 3. Acutely perceptive of interpersonal situations. 4. One who is readily hypnotizable. 5. Readily undergoing a chemical change, with but slight change in environmental conditions, as a s. reagent. 6. In immunology, denoting: 1) a sensitized antigen; 2) a person (or animal) rendered susceptible to immunological reactions by previous exposure to the antigen concerned. SYN: sensible (3) .

sensitivity (sen-si-tiv′i-te)
1. The ability to appreciate by one or more of the senses. 2. State of being sensitive. SYN: esthesia (2) . 3. In clinical pathology and medical screening, the proportion of affected individuals who give a positive test result for the disease that the test is intended to reveal, i.e., true positive results divided by total true positive and false negative results, usually expressed as a percentage. Cf.:specificity (2) . [L. sentio, pp. sensus, to feel] acquired s. SYN: allergy (1) . analytical s. 1. the minimum detection limit; 2. the degree of response to a change in concentration of analyte being measured in an assay. antibiotic s. microbial susceptibility to antibiotics. SEE ALSO: antibiotic s. test, minimal inhibitory concentration. clinical s. test positivity in disease; ability of a test to correctly identify disease. SEE ALSO: diagnostic s.. contrast s. in optics, the ability to discern the difference in brightness of adjacent areas; in radiology, allergic reaction to iodinated radiographic contrast medium. diagnostic s. the probability (P) that, given the presence of disease (D), an abnormal test result (T) indicates the presence of disease; i.e., P(T/D). SEE ALSO: clinical s.. idiosyncratic s. atopy, a type I allergic reaction. induced s. SYN: allergy (1) . multiple chemical s. a symptom array of variable presentation attributed to recurrent exposure to known environmental chemicals at dosages generally below levels established as harmful; complaints involve multiple organ systems. SYN: environmental illness. pacemaker s. the minimum cardiac activity required to consistently trigger a pulse generator. photoallergic s. photosensitization. phototoxic s. photosensitization. primaquine s. nonimmunologic inborn s. to primaquine, causing hemolysis on exposure to the drug, due to deficiency of glucose 6-phosphate dehydrogenase in red cells. relative s. the s. of a medical screening test as determined by comparison with the same type of test; e.g., s. of a new serologic test relative to s. of an established serologic test. salt s. the tendency of certain bacterial suspensions to agglutinate spontaneously in physiologic saline solution. spectral s. the reciprocal of the amount of monochromatic radiation that produces a fixed response.

sensitization (sen′si-ti-za′shun)
Immunization, especially with reference to antigens (immunogens) not associated with infection; the induction of acquired sensitivity or of allergy. autoerythrocyte s. autoerythrocyte s. syndrome. covert s. aversive conditioning or training to rid oneself of an unwanted behavior during which the patient is taught to imagine unpleasant and related aversive consequences while engaging in the unwanted habit. photodynamic s. the action by which certain substances, notably fluorescing dyes (acridine, eosin, methylene blue, rose bengal) absorb visible light and emit the energy at wavelengths that are deleterious to microbes or other organisms in the dye-containing suspension, or selectively destroy cancer cells sensitized by intravenous porphyrin and exposed to red laser light. SYN: photosensitization (2) .

sensitize (sen′si-tiz)
To render sensitive; to induce acquired sensitivity, to immunize. SEE ALSO: sensitized antigen.

sensitizer (sen′si-tiz-er)
1. A substance that causes allergy or dermatitis only after alteration (sensitization) of the skin by previous exposure to that substance. 2. SYN: antibody.

sensitometry (sen-si-tom′e-tre)
In radiology, the procedure of measuring film response to radiation. [sensitivity + G. metron, measure]

sensomobile (sen-so-mo′bel)
Capable of movement in response to a stimulus.

sensomobility (sen-so-mo-bil′i-te)
The state of being sensomobile.

sensomotor (sen-so-mo′ter)
SYN: sensorimotor.

sensor (sen′sor)
A device designed to respond to physical stimuli such as temperature, light, magnetism, or movement, and to transmit resulting impulses for interpretation, recording, movement, or operating control. See sense.

Sensory. [L. sensorius]

sensorial (sen-sor′e-al)
Relating to the sensorium.

sensoriglandular (sen′sor-i-glan′du-lar)
Relating to glandular secretion excited by stimulation of the sensory nerves.

sensorimotor (sen′sor-i-mo′ter)
Both sensory and motor; denoting a mixed nerve with afferent and efferent fibers. SYN: sensomotor.

sensorimuscular (sen′sor-i-mus′ku-lar)
Denoting muscular contraction in response to a sensory stimulus.

sensorium, pl .sensoriasensoriums (sen-sor′e-um, -a, -umz)
1. An organ of sensation. 2. The hypothetical “seat of sensation.” SYN: perceptorium. 3. In human biology and psychology, consciousness; sometimes used as a generic term for the intellectual and cognitive functions. [Late L.]

sensorivascular (sen′sor-i-vas′ku-lar)
SYN: sensorivasomotor.

sensorivasomotor (sen′sor-i-vas-o-mo′ter)
Denoting contraction or dilation of the blood vessels occurring as a sensory reflex. SYN: sensorivascular.


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