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

Newborn Brookfield Zoo dolphin calf dies suddenly A 4-day-old bottlenose dolphin born last weekend at the Brookfield Zoo Chicago died suddenly Wednesday. —Chicago Tribune, 13 June 2025

Related Articles Wild pigs increase around the Bay Area, causing headaches for homeowners, parks and water agencies Video shows dolphin calf birth and first breath at Chicago zoo. —Nate Gartrell, Mercury News, 12 June 2025

By creating a kind of prehistoric food web, the researchers placed animals like sea bream (which eat mussels and crustaceans) at the bottom, followed by smaller sharks and extinct toothed whales the size of modern dolphins. —Melissa Cristina Márquez, Forbes.com, 11 June 2025

Wade out to the sandbar at high tide, watch dolphins splash on the horizon, then linger at sunset when the sky dissolves into photo-worthy peaches and purples. —Allison Palmer, Charlotte Observer, 11 June 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