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

Dolphin : 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

The scientist told me repeatedly of escaping to the ship’s deck and surrounding himself with the openness of the ocean, the beauty of volcanic islands, the whales, the dolphins, the flying fish, and, above all, the seabirds. —Akash Kapur, New Yorker, 12 May 2026

Yenser said Texas guard DJ Campbell, picked by the Dolphins in the sixth round and 200th overall, left a lasting impression at his Pro Day. —Barry Jackson, Miami Herald, 12 May 2026

In a new study, researchers documented seven cases of remoras, a fish known for suctioning itself onto rays—as well as sharks, dolphins, boats and even divers—plunging into manta rays' cloacal orifice, an opening used for pooping, peeing and mating. —Jackie Flynn Mogensen, Scientific American, 11 May 2026

Herman is signing with the Dolphins as a fullback, according to the team’s press release. —David Furones, Sun Sentinel, 11 May 2026

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