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 Dolphins even recently signed a pair of kickers, punters and long snappers to that end. —Miami Herald, 20 Mar. 2026

Now, in just her third campaign, the Dolphins are conference champions with 24 wins — more than doubling their victory total from her debut season. —Ryan Brennan, Fort Worth Star-Telegram, 20 Mar. 2026

Forget scientific exploration under the seas; this is a story about the half-shark son of Marko named Sharko, dolphin supremacy, and a look at Jonathan Swift’s A Modest Proposal that makes the cannibalistic horror of the 300-year-old satire feel brand new. —Eric Vilas-Boas, Vulture, 18 Mar. 2026

His 1,350 rushing yards in 2025 rank third among Dolphins single-season totals, behind Ricky Williams’ 2002 and 2003 campaigns. —David Furones, Sun Sentinel, 18 Mar. 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