rooster

The word 'rooster' is a relatively modern American English formation from the late 18th century, created by applying the agent suffix '-er' to the verb 'roost', meaning to perch or settle for sleep. It literally means "one who roosts." This term emerged as a euphemistic alternative to the older, more direct term 'cock', which had begun to acquire vulgar connotations. The logic is transparent: it names the bird by one of its characteristic behaviors—perching on a roost at night—and exemplifies a pattern of word formation where an agent noun is derived from a verb to describe an animal by its habitual action.

Structure: roost (to settle for rest) + er (one who does) 'roost' (from Old English 'hrōst', meaning a perch or support for birds) + 'er' (agent noun suffix from Old English '-ere', indicating a person or thing associated with an action).