A cetacean of the genus Delphinus and allied genera (esp. D. delphis); the true dolphin.
- Any of various marine cetacean mammals, such as the bottle-nosed dolphin, of the family Delphinidae, related to the whales but generally smaller and having a beaklike snout.
- A large marine food and game fish (Coryphaena hippurus) found worldwide in tropical waters, having an iridescent blue back, yellow sides, a steep blunt forehead, and a long continuous dorsal fin. Also called dolphinfish, dorado, mahi-mahi.
- A similar fish (C. equisetis) of smaller size, having silvery or pale yellow sides. Also called dolphinfish, pompano dolphin.
- A buoy, pile, or group of piles used for mooring boats.
- A group of piers used as a fender at a dock.