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

"A dorsal fin slowly broke the surface revealing that familiar profile that looked like a shark," he said.

From BBC • May 16, 2025

Wide and pitch black, it had no dorsal fin.

From Seattle Times • May 27, 2024

The researchers call transients Orcinus rectipinnus, noting that, in Latin, “recti means right or upright, and pinna means fin, feather, or wing, most likely referring to the tall erect dorsal fin of males.”

From Los Angeles Times • Mar. 29, 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

An experienced fisherman would walk to the end of the plank, launching the tag into the shark’s dorsal fin.

From "The Line Tender" by Kate Allen