dorsal fin

noun

plural dorsal fins

: a flat thin body part that projects from the back of many fish (such as trout, barracuda, and sharks) and some marine mammals (such as dolphins)

Porpoises have a more triangular dorsal fin while a dolphin's dorsal fin is more curved.

—Naomi Corrigan and Dave Himelfield

This member of the perch family has two dorsal fins and a large mouth outfitted with sharp teeth …

—Matt Markey

Examples of dorsal fin in a Sentence

Recent Examples on the Web

Motor neurons for the first dorsal fin of filefish were found in the same location as motor neurons for the second, third and fourth dorsal fins in frogfish. —Elizabeth Rayne, Ars Technica, 30 Dec. 2024

Orcas have been spotted draping strands of kelp over their dorsal fins or tails, seemingly just for fun. —Scott Travers, Forbes, 25 Dec. 2024

Marine biologists have long wondered about the identity and exact location of the neurons that control the dorsal fin’s critical motor function. —Andrew Paul, Popular Science, 12 Dec. 2024

White sharks can be distinguished and identified based on their unique coloration, markings on the gills and fins, and dorsal fin profiles. —Rick Sobey, Boston Herald, 4 Apr. 2024

Unlike many other whales, such as orcas and blue whales, belugas have no dorsal fin. —Avery Hurt, Discover Magazine, 13 Dec. 2024

Anglerfish earned the name for their unique evolutionary hunting adaptation—a front dorsal fin known as an illicium that functions as a lure. —Andrew Paul, Popular Science, 12 Dec. 2024

Unlike the common carp, which has a long spiny dorsal fin and a whiskerlike barbel near its mouth, the white amur has a short dorsal fin with no spines. —John Leos, The Arizona Republic, 30 Nov. 2024

White sharks have a pointed dorsal fin, while basking sharks have a rounded fin. —Rick Sobey, Boston Herald, 28 May 2024

Word History

First Known Use

1752, in the meaning defined above

Kids Definition

dorsal fin

noun

: a fin on the ridge along the middle of the back of a fish or sea mammal (as a whale)