Definitions
1.nounA small cetacean of the family Phocoenidae, related to dolphins and whales.
2.noun(imprecisely) Any small dolphin.
3.verbSaid of an air-breathing aquatic animal such as a porpoise or penguin: To repeatedly jump out of the water to take a breath and dive back in a continuous motion.
4.verbSaid of an aircraft: to make a series of plunges when taking off or landing; or of a watercraft: to successively plunge up and down in the water.