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1630s, Scottish borrowing of French cachet "seal affixed to a letter or document" (16c.), from Old French dialectal cacher "to press, crowd," from Latin coactare "constrain" (see cache). Meaning evolving through "(letter under) personal stamp (of the king)" to "prestige." Cf. French lettre de cachet "letter under seal of the king."
cachet ca·chet (kā-shā')
An edible wafer capsule used for enclosing an unpleasant-tasting drug.