porpoise

Meanings

1. A small cetacean of the family Phocoenidae, related to dolphins and whales.
2. Any small dolphin.

1. 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.
2. 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.

Etymology

From Middle English porpeys, purpeys, borrowed from Anglo-Norman porpeis, purpeis, Old French pourpois, porpois, pourpais, porpeis (“porpoise”), from Vulgar Latin *porcopiscis (“porpoise”, literally “hog-fish”), taken from Latin porcus (“hog, pig”) + piscis (“fish”). Compare (in transposed order) obsolete Italian pesce porco and Portuguese peixe porco; also Latin porcus marīnus (“sea hog”); akin in formation to Frankish *mariswīn (“porpoise, dolphin”) (whence German Meerschwein, English mereswine). Displaced native Middle English brunswyn. More at mereswine.