sheathe (v.)

Middle English shethe, "close-fitting case or covering for a blade," from Old English sceaþ, scæþ, from Proto-Germanic *skaith- (source also of Old Saxon scethia, Old Norse skeiðir (plural), Old Frisian skethe, Middle Dutch schede, Dutch schede, Old High German skaida, German scheide "a sheath, scabbard"), perhaps from an extended form of PIE root *skei- "to cut, split," on the notion of a split stick with the sword blade inserted.

Extended to any somewhat similar tube-like covering by 1550s; the meaning "condom" is recorded from 1861; the sense of "close-fitting dress or skirt" is attested from 1904.

Proto-Indo-European root meaning "to cut, split," extension of root *sek- "to cut."

It forms all or part of: abscissa; conscience; conscious; ecu; escudo; escutcheon; esquire; nescience; nescient; nice; omniscience; omniscient; plebiscite; prescience; prescient; rescind; rescission; science; scienter; scilicet; sciolist; scission; schism; schist; schizo-; schizophrenia; scudo; sheath; sheathe; sheave (n.) "grooved wheel to receive a cord, pulley;" shed (v.) "cast off;" shin (n.) "fore part of the lower leg;" shingle (n.1) "thin piece of wood;" shit (v.); shive; shiver (n.1) "small piece, splinter, fragment, chip;" shoddy; shyster; skene; ski; skive (v.1) "split or cut into strips, pare off, grind away;" squire.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit chindhi, chinatti "to break, split up;" Avestan a-sista- "unsplit, unharmed," Greek skhizein "to split, cleave, part, separate;" Latin scindere "to cut, rend, tear asunder, split;" Armenian c'tim "to tear, scratch;" Lithuanian skiesti "to separate, divide;" Old Church Slavonic cediti "to strain;" Old English scitan, Old Norse skita "to defecate;" Old English sceað, Old High German sceida "sheath;" Old Irish sceid "to vomit, spit;" Welsh chwydu "to break open."

late 14c., from un- (2) "reverse, opposite of" + sheathe (v.). Related: Unsheathed; unsheathing.