dorsal fin

noun

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

dorsal fin

noun

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

Word History and Origins

Origin of dorsal fin¹

First recorded in 1760–70

Example Sentences

In Oregon, when a survey team first spotted a large fish rise to the surface, they saw only its dorsal fin, said Mark Hereford, Klamath fisheries reintroduction project leader for the Oregon Department of Fish and Wildlife.

From Los Angeles Times

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

From Los Angeles Times

Tadamichi Morisaka, a cetology professor at Japan's Mie University, said the dorsal fin of a dolphin spotted biting a man's fingers at a beach in Tsuruga - a port city next to Mihama - matched those of a 2.5m long dolphin observed off the coast of Fukui province last year.

From BBC

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

From BBC

Wide and pitch black, it had no dorsal fin.

From Seattle Times