dorsal fin

American  

noun

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

---

dorsal fin British  

noun

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

---

Etymology

Origin of dorsal fin

First recorded in 1760–70

Example Sentences

See Examples For:

dorsal fin

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

Wide and pitch black, it had no dorsal fin.

From Seattle Times ● May 27, 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

And unlike other mosasaurs, or large extinct marine reptiles, it had a dorsal fin like a shark's that would have helped it turn quickly and with precision in the water.

From Science Daily ● Dec. 12, 2023

Aru only had a second to glance back and see the dorsal fin that had scraped Mini’s ankle.

From "Aru Shah and the End of Time" by Roshani Chokshi