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

Kayaking with dolphins and humpback whales is one of the activities advertised on the government’s tourism website. —Abel Alvarado, CNN, 13 Feb. 2025

Plastic straws were also noted sticking out of sea turtle nostrils, and sickening or killing seabirds, fish, manatees, dolphins and other marine mammals. —Susanne Rust, Los Angeles Times, 12 Feb. 2025

Thankfully, many safari outfitters offer dynamic itineraries—think pairing the quintessential South African safari with a surreal stint in Namibia or a blue safari grand finale in Mozambique filled with whales, dolphins, whale sharks, and dugongs—designed to engage animal lovers of all ages. —Kathryn Romeyn, AFAR Media, 11 Feb. 2025

Like penguins, dolphins, and whales, people feel a strong connection to them. —Leanne Potts, Better Homes & Gardens, 8 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