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

They primarily rely on their dorsal fin, whereas strong swimmers use their caudal fin or back tail, Paig-Tran said.

From Los Angeles Times • Nov. 21, 2024

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

From BBC • Aug. 26, 2024

“I never thought I’d be holding the dorsal fin of a great white shark and applying this type of technology,” Michalove said.

From Seattle Times • May 23, 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

“The dorsal fin on a basking shark is rounded on top and convex in the back,” she said, making shapes with her hand.

From "The Line Tender" by Kate Allen