[pawr-puh
s] 
noun, plural (especially collectively) -poise, (especially referring to two or more kinds or species) -pois⋅es, verb, -poised, -pois⋅ing.| 1. | any of several small, gregarious cetaceans of the genus Phocoena, usually blackish above and paler beneath, and having a blunt, rounded snout, esp. the common porpoise, P. phocoena, of both the North Atlantic and Pacific. |
| 2. | any of several other small cetaceans, as the common dolphin, Delphinus delphis. |
| 3. | (of a speeding motorboat) to leap clear of the water after striking a wave. |
| 4. | (of a torpedo) to appear above the surface of the water. |
| 5. | to move forward with a rising and falling motion in the manner of a porpoise: The car has a tendency to porpoise when overloaded. |
| por·poise (pôr'pəs) n. pl. porpoise or por·pois·es
[Middle English porpeis, from Old French (probably translation of a Germanic compound meaning sea-pig) : porc, pig (from Latin porcus; see porko- in Indo-European roots) + peis, fish (from Latin piscis).] |
