dorsal fin

noun

the fin or finlike integumentary expansion generally developed on the back of aquatic vertebrates.

Origin of dorsal fin

First recorded in 1760–70

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for dorsal fin

Historical Examples of dorsal fin

In the figure there is represented the cross-section of a fish (its dorsal-fin D) just before the spear strikes.
Along Alaska's Great River
Frederick Schwatka

British Dictionary definitions for dorsal fin

dorsal fin

noun

any unpaired median fin on the backs of fishes and some other aquatic vertebrates: maintains balance during locomotion

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012