"mass of slag," 1769, from klincard (1640s), a type of paving brick made in Holland, from Dutch klinkaerd, from klinken "to ring" (as it does when struck), which is of imitative origin (compare clink (v.)). Also "a clinch-nail" (see clench, clinch). The meaning "stupid mistake" is first recorded 1950 in American English; originally (1942) "a wrong note in music."
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