Fiber (Lat. fibra, a filament). One of the tiny threads of which many parts of the body are composed.

Fibrilla. A little fiber; one of the longitudinal threads into which a striped muscular fiber can be divided.

Fibrin (Lat. fibra, a fiber). An albuminoid substance contained in the flesh of animals, and also produced by the coagulation of blood.

Flexion (Lat. flecto, to bend). The act of bending a limb, etc.

Follicle (Lat. dim. of follis, a money bag). A little pouch or depression.

Fomentation (Lat. foveo, to keep warm). The application of any warm, medicinal substance to the body, by which the vessels are relaxed.

Foramen. A hole, or aperture.

Frontal Sinus. A blind or closed cavity in the bones of the skull just over the eyebrows.

Fumigation (Lat. fumigo, to perfume a place). The use of certain fumes to counteract contagious effluvia.

Function (Lat. functio, a doing). The special duty of any organ.