ignore (v.)youdaoicibaDictYouDict[ignore 词源字典]
1610s, "not to know, to be ignorant of," from French ignorer "be unaware of," from Latin ignorare "not to know, disregard" (see ignorant). Sense of "pay no attention to" first recorded 1801 (Barnhart says "probably a dictionary word"), and not common until c. 1850. Related: Ignored; ignoring.[ignore etymology, ignore origin, 英语词源]
slight (n.)youdaoicibaDictYouDict
1550s, "small amount or weight," from slight (v.). Meaning "act of intentional neglect or ignoring out of displeasure or contempt" is from 1701, probably via 17c. phrase make a slight of (1610s).