A small cetacean of the family Phocoenidae, related to dolphins and whales.
Any small dolphin.
Said 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.
Said 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.
Any marine or freshwater fish of the family Acipenseridae that are prized for their roe and are endemic to temperate seas and rivers of the northern hemisphere, especially central Eurasia.