delete (v.)youdaoicibaDictYouDict[delete 词源字典]
late 15c., "destroy, eradicate," from Latin deletus, past participle of delere "destroy, blot out, efface," from delevi, originally perfective tense of delinere "to daub, erase by smudging" (as of the wax on a writing table), from de- "from, away" (see de-) + linere "to smear, wipe" (see lime (n.1)). In English, specifically of written matter, from c. 1600. Related: Deleted; deleting.[delete etymology, delete origin, 英语词源]
expletive (n.)youdaoicibaDictYouDict
1610s, "a word or phrase serving to fill out a sentence or metrical line," from Middle French explétif (15c.) and directly from Late Latin expletivus "serving to fill out," from explet-, past participle stem of Latin explere "fill out, fill up, glut," from ex- "out" (see ex-) + plere "to fill" (see pleio-).

Sense of "an exclamation," especially "a curse word, an oath," first recorded 1815 in Sir Walter Scott, popularized by edited transcripts of Watergate tapes (mid-1970s), in which expletive deleted replaced President Nixon's salty expressions. As an adjective, from 1660s.
gunsel (n.)youdaoicibaDictYouDict
1914, American English underworld slang, from hobo slang, "a catamite;" specifically "a young male kept as a sexual companion, especially by an older tramp," from Yiddish genzel, from German Gänslein "gosling, young goose" (see goose (n.)). The secondary, non-sexual meaning "young hoodlum" seems to be entirely traceable to Dashiell Hammett, who sneaked it into "The Maltese Falcon" (1929) while warring with his editor over the book's racy language:
"Another thing," Spade repeated, glaring at the boy: "Keep that gunsel away from me while you're making up your mind. I'll kill him."
The context implies some connection with gun and a sense of "gunman," and evidently that is what the editor believed it to mean. The word was retained in the script of the 1941 movie made from the book, so evidently the Motion Picture Production Code censors didn't know it either.
The relationship between Kasper Gutman (Sidney Greenstreet) and his young hit-man companion, Wilmer Cook (Elisha Cook, Jr.), is made fairly clear in the movie, but the overt mention of sexual perversion would have been deleted if the censors hadn't made the same mistaken assumption as Hammett's editor. [Hugh Rawson, "Wicked Words," 1989, p.184]
index (n.)youdaoicibaDictYouDict
late 14c., "the forefinger," from Latin index (genitive indicis) "forefinger, pointer, sign, list," literally "anything which points out," from indicare "point out" (see indication). Meaning "list of a book's contents" is first attested 1570s, from Latin phrases such as Index Nominum "Index of Names," index expurgatorius "specification of passages to be deleted from works otherwise permitted." Scientific sense (refractive index, etc.) is from 1829; economic sense (cost-of-living index, etc.) is from 1870, from the scientific usage, from sense "an indicator." The Church sense of "forbidden books" is from index librorum prohibitorum, first published 1564 by authority of Pius IV.