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1570s, "to reduce to order, to set out clearly" (of accounts), from Late Latin or Medieval Latin liquidatus, past participle of liquidare "to melt, make liquid or clear, clarify," from Latin liquidus (see liquid). Sense of "clear away" (a debt) first recorded 1755. The meaning "wipe out, kill" is from 1924, possibly from Russian likvidirovat. Related: Liquidated; liquidating.
[1924+; based on Russian likvidirovat, ''liquidate, wind up'']