dolphin

noun

dol·​phin ˈdäl-fən 

ˈdȯl-

1

a

: any of various small marine toothed whales (family Delphinidae) with the snout more or less elongated into a beak and the neck vertebrae partially fused

Note: While not closely related, dolphins and porpoises share a physical resemblance that often leads to misidentification. Dolphins typically have cone-shaped teeth, curved dorsal fins, and elongated beaks with large mouths, while porpoises have flat, spade-shaped teeth, triangular dorsal fins, and shortened beaks with smaller mouths.

b

: any of several related chiefly freshwater toothed whales (as of the families Platanistidae and Iniidae) : river dolphin

2

: dolphinfish

3

capitalized : delphinus

4

: a spar or buoy for mooring boats

also : a cluster of closely driven piles used as a fender for a dock or as a mooring or guide for boats

Illustration of dolphin

• dolphin 1a

Examples of dolphin in a Sentence

Recent Examples on the Web

After so much activity, my favorite moment of the trip—besides the dolphin encounter, of course—was actually a moment of quiet on the 11th day of the journey. —Stefanie Waldek, AFAR Media, 12 Sep. 2025

That could mean preserving the Seaquarium’s aquarium as an attraction while the Dolphin Company relocates or sells to competitors the dolphins, sea lions and other mammals that have long been the stars of the park. —Douglas Hanks, Miami Herald, 12 Sep. 2025

Off the shores of the island lie rainbow coral reefs, seagrass beds, and undersea ridges sheltering hundreds of species of fish, dugongs, and 15 species of dolphins and whales. —M. Rajshekhar, Time, 11 Sep. 2025

Take a Kayak Tour Explore area wildlife—like manatees, birds, and dolphins—by boat with Adventure Kayak Outfitters. —Lisa Cericola, Southern Living, 5 Sep. 2025

Word History

Etymology

Middle English delphyn, dolphyn, from Anglo-French delphin, alteration of Old French dalfin, from Medieval Latin dalfinus, alteration of Latin delphinus, from Greek delphin-, delphis; akin to Greek delphys womb, Sanskrit garbha

First Known Use

14th century, in the meaning defined at sense 1a(1)

Phrases Containing dolphin

• bottle-nosed dolphin
• bottlenose dolphin
• dolphin striker
• Risso's dolphin
• river dolphin
• spinner dolphin

Kids Definition

dolphin

noun

dol·​phin ˈdäl-fən 

ˈdȯl-

1

a

: any of various small whales with teeth and a long nose

b

: porpoise sense 1

2

: either of two active saltwater food fishes noted for their brilliant coloring