The word 'zippered' is a modern English formation that illustrates the process of turning a trademarked object name into a descriptive adjective. Its core, 'zipper', is itself a creative 20th-century invention, built upon the imitative sound 'zip' to name a new type of fastening device. The addition of the adjectival suffix '-ed', a versatile morpheme with ancient Germanic roots, follows a standard English pattern (as in 'buttoned', 'gloved') to mean "equipped with or secured by a zipper". Thus, the term's logic is transparent: it directly describes the state of having the characteristic feature (a zipper) attached or employed.

Structure: zipper (fastening device) + ed (adjective-forming suffix) - zipper: A 20th-century English coinage, originally a trademark (B.F. Goodrich, 1925), derived from the onomatopoeic word 'zip' (imitative of a sharp, light sound) + the agent suffix '-er'. It functions as the base noun. - ed: A productive English suffix of Old English origin, used to form adjectives from nouns, meaning "having, provided with, or characterized by".