dorsal fin

American  

noun

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

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dorsal fin British  

noun

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

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Etymology

Origin of dorsal fin

First recorded in 1760–70

Example Sentences

Winter had put a life vest on the dog resembling a shark, with a dorsal fin protruding from its back.

From Los Angeles Times • Oct. 9, 2024

The dorsal fin is like a dolphin's fingerprint, as each has distinctive notches, ridges and pigmentation.

From BBC • Aug. 26, 2024

Gray whales are easily distinguished from other whales “by their lack of a dorsal fin, mottled grey and white skin, and dorsal hump followed by pronounced ridges,” according to the aquarium.

From Seattle Times • Mar. 6, 2024

What they spotted, a whale without a dorsal fin, led the researchers to think that it might be a North Atlantic right whale, a critically endangered species that the aquarium has been closely monitoring.

From New York Times • Mar. 6, 2024

This time, she was in a group of people, standing at the water’s edge, looking at a dorsal fin poking out from the flat calm.

From "The Line Tender" by Kate Allen