babble (v.)youdaoicibaDictYouDict[babble 词源字典]
mid-13c., babeln "to prattle, chatter," akin to other Western European words for stammering and prattling (cognates: Swedish babbla, Old French babillier) attested from the same era, some of which probably were borrowed from others, but etymologists cannot now determine which were original. Probably imitative of baby-talk, in any case (compare Latin babulus "babbler," Greek barbaros "non-Greek-speaking"). "No direct connexion with Babel can be traced; though association with that may have affected the senses" [OED]. Meaning "to repeat oneself incoherently, speak foolishly" is attested from c. 1400. Related: Babbled; babbler; babbling; babblement.[babble etymology, babble origin, 英语词源]
hillbilly (n.)youdaoicibaDictYouDict
"southern Appalachian U.S. resident," by 1892, from hill + masc. proper name Billy/Billie.
Then again, I do not think It will do so well. I would hate to see some old railroad man come here and take my job, and then, I don t think It is right to hire some Hill Billy and give him the same right as I just because he was hired the same time I was. ["The Railroad Trainmen's Journal," vol. IX, July 1892]


In short, a Hill-Billie is a free and untrammelled white citizen of Alabama, who lives in the hills, has no means to speak of, dresses as he can, talks as he pleases, drinks whiskey when he gets it, and fires of his revolver as the fancy takes him. ["New York Journal," April 23, 1900]
In reference to a type of folk music, first attested 1924.
tank (v.)youdaoicibaDictYouDict
1900, "to put into a tank," from tank (n.). Meaning "to lose or fail" attested from 1976, originally in tennis jargon, specifically in an interview with Billie Jean King in "Life" magazine, Sept. 22, 1967:
"When our men don't feel like trying," she says, "They 'tank' [give up]. I never tanked a match in my life and I never saw a girl do it. The men do it all the time in minor tournaments when they don't feel like hustling. You have to be horribly competitive to win in big-time tennis."
Sometimes said to be from boxing, in some sense, perhaps from the notion of "taking a dive," but evidence for this is wanting. Related: Tanked; tanking. Adjective tanked "drunk" is from 1893.