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

Watch: Fishermen steer 900-pound dolphin to safety Video footage from the incident shows the dolphin lying on the boat as one of the men steers the boat while another waters it with a hose. —Saman Shafiq, USA TODAY, 6 Mar. 2025

He’s gone Jet Skiing with dolphins in The Maldives and snowmobiling with his hotel butler in Türkiye — all in search of a great story. —Adam Morganstern, Forbes, 4 Mar. 2025

Onlookers also got to see five gray whales, 300 other northern right whale dolphins, 20 Risso’s dolphins, five humpback whales and two bottlenose dolphins the same day, the group said on Facebook. —Paloma Chavez, Sacramento Bee, 3 Mar. 2025

By the end of the ride, the group had counted more than 2,000 dolphins, including light gray baby calves, several hundred Pacific white-sided dolphins, and northern right whale dolphins. —Charlotte Phillipp, People.com, 28 Feb. 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