Prophylaxis (Gr. propkylassein, to keep guard before), prevention or warding off of disease.

Prostate (Gr. prostates, prostate), the name of a gland situated in front of the mouth of the bladder.

Protagon (Gr. protos, first, and agcin, to lead), a crystalline substance discovered in nervous tissue.

Proteid (Gr. protos, first), a general term for the albuminous and albuminoid constituents of the organism.

Protoplasm (Gr. protos, first; plasma, anything formed or moulded), the slimy albuminoid material resembling white of egg, constituting the basis of living plant or animal cells; living matter in its simplest form.

Protozoa (Gr. protos, first; zoon, animal), the lowest class of the animal kingdom, which consist of simple cells or colonies of cells.

Prurigo (Lat. prurire, to itch), a chronic papular inflammation of the skin attended with severe itching.

Pseudoplasm (Gr. pseudes, false, and plasma, a thing moulded), a new growth or tumour.

Psoriasis (Gr. psora, the itch), a chronic disease of the skin, distinguished by the presence of white scales on a red base ; dry tetter.

Psorosperms (Gr. psora, the itch; sperma, seed), a name for the sporozoa.

Pterygoid (Gr. pteryx, wing; eidos, shape), wing-shaped.

Ptomaine (Gr. ptoma, corpse), any of the toxic or poisonous substances resulting from the decomposition or decay of animal matter.

Ptyalin (Gr. ptyalon, saliva), a ferment found in saliva, having the property of converting starch into sugar.

Pubis (Lat), the os pubis or pubic bone at the lower part of the abdomen and connected with the pelvis.

Pupa (Lat. pupa, a doll), the second stage of development from the egg of those insects which undergo complete metamorphosis; the chrysalis.

Pupil (Lat. pupilla), the round opening admitting light in the iris of the eye.

Purpura (Lat. purpura), an eruption of purple spots in the skin. Purpura haemorrhagica, an aggravated form of purpura extending over the whole body.

Pylorus (Gr. pyloros, gatekeeper), the outlet or opening of the stomach into the duodenum.

Pyriformis (Lat. pyrus, pear; forma, a form), pear-shaped ; a term applied to a muscle within the pelvis.


Racemose (Lat. racemus, a bunch of grapes), having a shape resembling a bunch of grapes.

Radius (Lat. radius, a staff, rod, spoke), one of the two large bones of the forearm ; in the horse, a bone of the foreleg between the humerus and the knee.

Receptive (Lat. recipere, to receive), having the quality for receiving.

Rectum (Lat. rectus, straight), the posterior part of the large intestine.

Recurrent (Lat. rccurrere, to run back), recurring, reappearing.

Reflex (Lat. reflexus, thrown back), applied to the action of a part upon the application of a stimulus to another and distant part.

Regurgitation (Lat. re, again ; gurgitare, to engulf), an eructation or throwing back.

Renal (Lat. renalis - ren, a kidney), pertaining to the kidneys.

Repellent (Lat. repellere, to repel), having the power to repel morbid processes.

Rete mucosum (Lat. rete, a net; mucus, mucous), the lower layer of living cells in the epidermis.

Rhizome (Gr. rhiza, root), a subterranean stem having roots at its nodes and a bud at its apex.

Rugae (Lat., wrinkles), foldings or creasings of an organ, as in the mucous membrane of the stomach, &c.

Rumination (Lat. ruminare, to chew the cud), the chewing of the cud, the returning of the food from the stomach and its remastication.


Saccnaromyces (Gr. saccharon, sugar, and mykes, fungus), a unicellular vegetable organism similar to the yeast plant.

Sacrum (Lat. saccr, sacred), a triangular bone composed of five pieces (vertebrae), forming a portion of the vertebral column (spine or backbone), and belonging to the pelvis.

Sagittal (Lat. sagitta, an arrow), referring to the suture uniting the parietal bones.

Sanguine (Lat. sanguis, blood), applied to an active, energetic disposition.

Sapid (Lat. sapere, to taste), capable of being tasted; having taste or savour.

Sarcinococcus (Lat. sareina, a bundle), a name of round or ovoid bacteria dividing in three directions, producing cubic masses of various sizes.

Sarcolemma (Gr. sarx, flesh, and lemma, husk), the membrane that envelops a muscle fibre.

Sartorius (Lat. sartor, tailor), a long slender muscle situated on the inner and front part of the thigh.

Scaphoid (Gr. scaphe, boat, and eidos, shape), a bone of the knee.

Scarification (Lat. scarificare, to scarify), to puncture a swollen part with a sharp scalpel, to let out effused serum, blood, or gases.

Schneiderian membrane (from a German anatomist, Schneider), the membrane lining the nose.

Scirrhus (Gr. skirrhos, a tumour), a kind of cancer, a hard cancer.

Scleroderma (Gr. skleros, hard, and derma, skin), a disease in which the skin becomes stiff and hard.

Sclerotic (Gr. skleros, hard), pertaining to the outer white, opaque, coat of the eye.

Scrotum (Lat.), the pouch containing the testicles.

Scutiform (Lat. scutus, a shield), shield-shaped.

Sebaceous (Lat. sebum, suet, fat), pertaining to the fat-secreting glands of the skin.

Semiology (Gr. srmeion, sign; logos, discourse), all that is known in regard to the symptoms of disease.

Sensory (Lat. sentirc, sensum, to feel), a term applied to a class of nerves which transmit sensation to certain parts.

Septic (Gr. septikos, putrefying), relating to putrefaction.

Septicaemia (Gr. septos, putrid; haima, blood), a condition of the blood induced by the absorption of septic products.

Septum (Lat.), a partition or division wall separating one cavity from another.

Sesamoid (Lat. sesamon, a kind of seed, and eidos, form), resembling a sesame seed, a term for small bones situated in tendons about joints, and others similarly situated.