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

Passed by primates, dolphins, elephants and even certain fish, the test has been thought to measure social intelligence. —Christian Thorsberg, Smithsonian Magazine, 4 Apr. 2024

Critics say that noise could disrupt marine mammals such as whales and dolphins, while plumes of sediment, potentially containing toxic compounds, kicked up by equipment on the seabed may disperse, harming midwater ecosystems, according to recent research. —Katie Hunt, CNN, 3 Apr. 2024

Mammals are not solely terrestrial; some are fully aquatic, including whales and dolphins, the University of Michigan Museum of Zoology reports. —Olivia Munson, USA TODAY, 1 Apr. 2024

The group photographs the marine debris for an open source database, logs other details such as the severity of wounds and entrapped animals’ locations, and is routinely called to help other entangled or otherwise imperiled animals, among them whales, dolphins, sharks, turtles and seabirds. —Cara Buckley, New York Times, 26 Mar. 2024

Well besides us and a few other mammals, like dolphins and bats, amongst the other vertebrate lineages, only birds have species that evolved vocal learning. —Nicholas Stfleur, STAT, 15 Mar. 2024

Between the county and the USDA, MS Leisure Company received notices that several areas in the park were unsafe and not structurally sound, including enclosures for the whales, penguins, parrots, dolphins and sea lions. —Ayana Archie, NPR, 8 Mar. 2024

Older and more vulnerable bridges can be retrofitted to add defensive infrastructure like dolphins, Leon said, but building them can cost hundreds of millions of dollars. —Minyvonne Burke, NBC News, 27 Mar. 2024

Why aren’t there freshwater seals or dolphins in the Great Lakes? —Smithsonian Magazine, Smithsonian Magazine, 27 Mar. 2024

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

• bottlenose dolphin
• dolphin striker
• spinner dolphin
• Risso's dolphin
• river dolphin
• bottle-nosed 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