The compound adjective 'three-man' is a straightforward modern English formation, combining the cardinal number 'three' and the noun 'man'. The number 'three' traces back to the Proto-Indo-European root trei-, which is the source for the concept of three across many languages, including its direct descendant in Old English. The word 'man' originates from the Proto-Germanic mann-, a term for a person, which became specialized in English to primarily denote a male adult. The compound logically follows the common English pattern of number-noun combinations used attributively (e.g., two-door, five-year), creating a concise descriptor for a group or unit composed of three male individuals.

Structure: three (number) + man (adult male) - three: From Old English þrīe, þrēo, of Proto-Germanic origin; related to Dutch drie and German drei, from an Indo-European root shared by Latin tres and Greek treis. Functions as a cardinal number. - man: From Old English mann, of Germanic origin; related to Dutch man and German Mann. Functions as a noun denoting an adult male human.