filled-in

The compound adjective 'filled-in' is a modern English formation built upon the core Germanic verb 'fill'. Its construction follows the standard participial pattern: the verb 'fill' takes the '-ed' suffix to create the past participle 'filled', denoting a completed state. The adverbial particle 'in' is then appended, a common feature in phrasal verbs and their derived adjectives, specifying the action as directed into a defined space or context. Thus, the literal sense of "having had something put into it" evolved logically into the figurative meanings of completing a form or briefing a person, where abstract information is metaphorically placed into empty sections or a mind.

Structure: fill + ed + in - fill: From Old English fyllan (to fill, make full). A verb root. - ed: A suffix of Old English origin, forming the past participle of verbs. - in: From Old English in (in, into). An adverbial particle.