O.E.
smoc "woman's garment," from P.Gmc.
*smukkaz (cf. O.N.
smokkr, but this is perhaps from O.E., O.H.G.
smoccho "smock," a rare word, N.Fris.
smok, but this, too, perhaps from Eng.), from PIE base
*smeugh- "to press" (cf. O.C.S.
smykati se "to creep"). Original notion seems to be "garment one creeps into," as the word is related to O.N.
smjuga "to creep into (a garment)" and O.E.
smugan "to creep" and
smygel "a burrow." Cf. also Ger.
schmiegen "to cling to, to press close, nestle," hence M.H.G. verb
smucken, Ger.
schmucken "to adorn." Eng.
smock was common down to 18c., and was emblematic of womanhood generally, cf. verb
smock "to render (a man) effeminate or womanish" (1614);
smock-face "person having a pale, effeminate face" (1605). Replaced by euphemistic
shift (n.2). Modern meaning "woman's or child's loose dress or blouse" is from 1907; sense of "loose garment worn by artists over other clothes" is from 1938.
[smok-ing] 
