finning

noun

1. any of several winglike, membranous organs on the body of a fish, dolphin, etc., used in swimming, turning, and balancing
2. anything like a fin in shape or use; specif.,
   1. any narrow edge or ridge formed in manufacturing, as on a casting by metal forced through the halves of the mold
   2. any vertical airfoil, fixed or movable, whose chief function is to give stability in flight
   3. a stabilizing or steering projection on boats or submarines
   4. Slang a hand or arm

transitive verb finned, finning

intransitive verb