"light, loose upper garment of linen or cotton," 1828 (from 1822 as a French word in English), from French blouse, "workman's or peasant's smock" (1788), origin unknown. Perhaps akin to Provençal (lano) blouso "short (wool)" [Gamillscheg]. Another suggestion [Klein] is that it is from Medieval Latin pelusia, from Pelusium, a city in Upper Egypt, supposedly a clothing manufacturing center in the Middle Ages. At first a garment worn by French working-men as a protection from dust, etc., later adopted fashionably for women and children, not without objection:
In Paris, a very slovenly, loose, drawn frock, with most capacious sleeves, had been introduced called a blouse. Some of our priestesses of the toilet seemed emulous of copying this deshabille, with some slight alterations, but we never wish to see it on the symmetrical form of a British lady. ["Summary of Fashion for 1822," in Museum of Foreign Literature and Science, Jan.-June 1823]
"rural person of inferior rank or condition," usually engaged in agricultural labor, early 15c., paisaunt, from Anglo-French paisant (early 14c.), Old French paisant, paisent "local inhabitant" (12c., Modern French paysan), earlier paisenc, from pais "country, region" (Modern French pays, from Latin pagus; see pagan) + Frankish suffix -enc "-ing."
Pais is from Late Latin pagensis "(inhabitant) of the district," from Latin pagus "country or rural district" (see pagan). As a style of garment in fashion (such as peasant blouse) from 1953. In German history, the Peasants' War was the rebellion of 1524-25.
Klein's sources, Barnhart and the OED see this as connected to a group of Germanic sm- words having to do with creeping or pressing close, such as Old Norse smjuga "to creep (through an opening), to put on (a garment)," smuga "narrow cleft to creep through; small hole;" Old Swedish smog "a round hole for the head;" Old English smugan, smeogan "to creep," smygel "a burrow." Compare also German schmiegen "to cling to, press close, nestle;" and Schmuck "jewelry, adornments," from schmucken "to adorn," literally "to dress up."
Watkins, however, traces it to a possible Germanic base *(s)muk- "wetness," figuratively "slipperiness," from PIE root*meug- "slimy, slippery" (see mucus). Either way, the original notion, then, seems generally to have been "garment one creeps or slips into," by the same pattern that produced sleeve and slip (n.2).
Now replaced by euphemistic shift (n.2); smock was the common word down to 18c., and was emblematic of womanhood generally, as in verb smock "to render (a man) effeminate or womanish" (1610s); smocker "man who consorts with women" (18c.); smock-face "person having a pale, effeminate face" (c. 1600). A smock-race (1707) was an old country pastime, a foot-race for women and girls with a smock as a prize. 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.