late 14c., "act of making or state of being compact," from Old French compaction, from Latin compactionem (nominative compactio) "a putting or joining together," noun of action from past participle stem of compingere "to fasten together, construct," from com "with, together" (see com-) + pangere "to fix, fasten" (from PIE root *pag- "to fasten"). From 1520s as "the making of a compact."
