- 1. A thin wing-like projection on a fish's body consisting of a thin fold of skin supported by bone or cartilage, used for propelling the fish through the water, balancing, steering, display and in some cases protection.
2. Anything that resembles a fin in appearance or function, eg the vertical projection in the tail of an aircraft, a blade projecting from the hull of a ship, a swimmer's flipper, attachments on 1950s cars.
- 1. To provide something with fins.
2. To cut off the fins from a fish.