late 14c., "a barrier, a fence," from Old French closure "enclosure; that which encloses, fastening, hedge, wall, fence," also closture "barrier, division; enclosure, hedge, fence, wall" (12c., Modern French clôture), from Late Latin clausura "lock, fortress, a closing" (source of Italian chiusura), from past participle stem of Latin claudere "to close" (see close (v.)).
Sense of "act of closing, a bringing to a close" is from early 15c. In legislation, especially "closing or stopping of debate" (compare cloture). Sense of "tendency to create ordered and satisfying wholes" is 1924, from Gestalt psychology.