dol·​phin ˈdäl-fən How to pronounce dolphin (audio)
: 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.

: any of several related chiefly freshwater toothed whales (as of the families Platanistidae and Iniidae) : river dolphin
capitalized : delphinus
: 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

Illustration of dolphin
  • dolphin 1a

Example Sentences

Recent Examples on the Web Jennifer Garner is encouraging Jennifer Coolidge to keep swimming towards her dream of one day playing a dolphin on screen. Emlyn Travis,, 14 Jan. 2023 Her special talent is sounding like a dolphin, per the fun facts portion of her bio. Emily Deletter, The Enquirer, 7 Jan. 2023 The beach-loving canine gets sucked into a swirling whirlpool where she is befriended by a dolphin and dines on an array of seafood before being deposited on a distant unknown shore somewhere in the Mediterranean. Diane Bellcolumnist, San Diego Union-Tribune, 7 Jan. 2023 Scientifically known as Shonisaurus popularis, the species resembled a chunky dolphin and grew at least 50 feet (15.2 meters) long. Katie Hunt, CNN, 19 Dec. 2022 Chaos then ensues, as Cannon struggles to check off the items on his kids’ wishlists, from a dolphin and a Playstation 5 to the Los Angeles Lakers. Rania Aniftos, Billboard, 1 Dec. 2022 The book is filled with enthralling facts, like the way that a dolphin echolocating a human in water can perceive not only the human’s outer shape but also what’s inside, including skeleton and lungs. The New York Times Books Staff, New York Times, 22 Nov. 2022 Some whale temples studied for the paper had acquired just a single carcass since the 19th century, others received a dead dolphin or whale every month, often of differing species. Smithsonian Magazine, 13 Sep. 2022 Seaquarium staff shared detailed records for each dolphin in the collection and full access to professional staff, medical records, and facilities. Glenn Garner, Peoplemag, 1 Nov. 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'dolphin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History


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)

Time Traveler
The first known use of dolphin was in the 14th century

Dictionary Entries Near dolphin

Cite this Entry

“Dolphin.” Dictionary, Merriam-Webster, Accessed 27 Jan. 2023.

Kids Definition


dol·​phin ˈdäl-fən How to pronounce dolphin (audio)
: any of various small whales with teeth and a long nose
: either of two active saltwater food fishes noted for their brilliant coloring

More from Merriam-Webster on dolphin

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