any of several large, oceanic hydrozoans of the genus Physalia, having a large, bladderlike structure with a saillike crest by which they are buoyed up and from which dangle tentacles with stinging cells.
Origin
1700-10
British Dictionary definitions for Portuguese man-of-war
Portuguese man-of-war
noun
1.
any of several large complex colonial hydrozoans of the genus Physalia, esp P. physalis, having an aerial float and long stinging tentacles: order SiphonophoraSometimes shortened to man-of-war