complement
n.
late 14c., "that which completes," from Old French compliement "accomplishment, fulfillment" (14c., Modern French complément), from Latin complementum "that which fills up or completes," from complere "fill up" (see complete, adj.). Originally also having senses which were taken up c.1650-1725 by compliment.
v.
1610s, "exchange courtesies," from complement, n.. Meaning "make complete" is from 1640s. Related: Complemented; complementing.
〔李〕[com- = together 一起；ple = to fill 装满；-ment n. = the means表手段→“the means of filling together一起填满的手段”→]Ⅰn. something that completes or makes perfect补充，补充物