Original: Etymology The Portuguese Man O ' War ( named caravela-portuguesa in Portuguese ) is named for its air bladder , which looks similar to the triangular sails of the Portuguese ship ( man-of-war ) Caravela latina ( two - or three-masted lateen-rigged ship caravel ) , of the 15th and 16th centuries .
Simplified: The common name comes from a Portuguese war ship type of the 15th and 16th century , the man-of-war ( named caravela-portuguesa in Portuguese , caravel ) .