Our online medical glossary of medical terms and definitions includes definitions for terms related to treatment, and general medicine
1. An organ of a fish, consisting of a membrane supported by rays, or few bony or cartilaginous ossicles, and serving to balance and propel it in the water.
Fishes movethrough the water chiefly by means of the caudalfin or tail, the principal office of the another fins being to balance or direct the body, though they are also, to a determined extent, employed in producing motion.
2. A membranous, finlike, swimming organ, as in pteropod and heteropod mollusks.
3. A finlike organ or attachment; a part of an object or product which protrudes like a fin, as: The hand.
4. A finlike appendage, as to submarine boats. Apidose fin.
5. The dorsal, caudal, and anal fins.
Origin: OE. Finne, fin, AS. Finn; akin to D. Vin, G. & Dan. Finne, Sw. Fena, L. Pinna, penna, a wing, feather. Cf. Pen a feather.