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"to complain, whine," 1953 (implied in kvetching), from Yiddish kvetshn, literally "squeeze, press," from German quetsche "crusher, presser." As a noun, from 1936 as a term of abuse for a person.
To work hard and seriously; stop loafing; buckle down
[1866+; fr the act of putting one's knuckles down to the taw or marble preparing for a careful shot in the game of marbles, a use dating fr the mid-18th century]