"wall separating two cavities," especially "the partition between the nostrils," 1690s, Modern Latin, from Latin saeptum "a fence, enclosure, partition," from neuter past participle of saepire "to hedge in," from saepes"a hedge, a fence," which de Vaan suggests is from a PIE *seh-i- "to tie." Related: Septal.

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.

also rhachio-, before vowels rachi-, word-forming element meaning "spinal, pertaining to the vertebrae," from Latinized form of Greek rhakhis "spine, back," metaphorically "ridge (of a mountain), rib of a leaf," a word of uncertain origin. Compare Greek rhakhos "thorn hedge."

"clumsy or awkward youth," 1530s, of uncertain origin and the subject of much discussion. Suspicion has focused on French or Anglo-French, but no appropriate word has been found there. First element is probably hob in its sense of "clown, prankster" (see hobgoblin), the second element perhaps is French de haye "worthless, untamed, wild," literally "of the hedge."