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

The opposition continues to perpetuate false narratives about purported harms to whales and dolphins, undeterred by the lack of scientific evidence. —Anna Broughel, Forbes.com, 7 Aug. 2025

Breakfast and balloons at Goldsmith Elementary At Goldsmith Elementary, a colorful balloon arch with dolphin balloons welcomed students on the first day. —Krista Johnson, The Courier-Journal, 7 Aug. 2025

If couples have little ones joining them, the resort is known to have the Indian Ocean’s biggest kid’s club, where children can even go dolphin scouting along the white sand beaches. —Elise Taylor, Vogue, 4 Aug. 2025

During a July 30 adventure, boaters got the chance to see Casper, an all white Risso’s dolphin, according to a Facebook post by the Monterey Bay Whale Watch. —Paloma Chavez august 1, Sacbee.com, 1 Aug. 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