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fin¹

(fĭn)

1. A membranous appendage extending from the body of a fish or other aquatic animal, used for propelling, steering, or balancing the body in the water.

2. Something resembling a fin in shape or function, as:

a. A covering for the foot having a flat flexible portion made of rubber or plastic that widens as it extends forward from the toes, used to provide enhanced propulsion in swimming and diving. Also called flipper.

b. A fixed or movable airfoil used to stabilize an aircraft, missile, or projectile in flight.

c. A thin, usually curved projection attached to the rear bottom of a surfboard for stability.

d. A projecting vane used for cooling, as on a radiator or an engine cylinder.

e. See tail fin.

v. finned, fin·ning, fins

v. tr.

1. To equip with fins.

2. To remove the fins from (a shark) and discard the rest of the shark's carcass: It's illegal to fin sharks in United States territorial waters.

v. intr.

1. To emerge with the fins above water.

2. To swim, as a fish.

Phrasal Verb:

fin out

To lash the water with the fins. Used of a dying whale.

[Middle English, from Old English finn.]

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fin¹

(click for a larger image)

fin¹

top: fins of a typical bony fish

bottom: swimming fins

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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