: 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
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
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Take a Kayak Tour Explore area wildlife—like manatees, birds, and dolphins—by boat with Adventure Kayak Outfitters.—Lisa Cericola, Southern Living, 5 Sep. 2025 Along with offering a classic beach day, Beachwalker Park is a great spot to see dolphins feeding or watch the sunset.—Lydia Mansel, Travel + Leisure, 2 Sep. 2025 The day for the boaters began with a lot of activity, starting with watching dolphins, followed by the fin whale sighting, which led them to the swordfish.—Paloma Chavez, Sacbee.com, 2 Sep. 2025 Onsite activities like a dolphin waverunner tour and parasailing adventure are also part of the sweepstakes.—Ramsey Qubein, Forbes.com, 1 Sep. 2025 See All Example Sentences for dolphin
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)
Time Traveler
The first known use of dolphin was
in the 14th century
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