man-of-war
UK[ˌmæn əv ˈwɔː]US[ˌmæn əv ˈwɔːr]
n
A warship, especially one armed with cannon and propelled by sails.
n
A large, often colonial, marine hydrozoan of the genus *Physalia*, having a venomous sting; the Portuguese man-of-war.
Etymology
The term 'man-of-war' is a fascinating example of a metaphorical compound that entered English as a complete unit. It originated in the late 15th century from the earlier phrase 'man of war,' a direct calque (loan translation) from the Old French 'homme de guerre,' meaning 'soldier.' The logic of the term is purely figurative: just as a soldier is a 'man of war,' so too is a powerful, armed sailing ship. This metaphorical naming reflects the anthropomorphism common in naval terminology, attributing human qualities of strength and aggression to a vessel. The application of the same name to the dangerous, sail-like marine organism Physalia is a later, descriptive analogy based on its resemblance to a warship under full sail.
Analysis
This is a fixed, idiomatic compound phrase. It cannot be meaningfully segmented into productive morphemes for analysis without losing its idiomatic sense. The phrase functions as a single lexical unit.
Examples
The Spanish man-of-war dominated the seas during the Age of Exploration.
He was warned not to swim in the bay because of sightings of the Portuguese man-of-war.
Nelson's fleet included several formidable 74-gun men-of-war.