In English, one-piece is a type of swimsuit, but in Korean, a onepiece is a dress.
Obviously, though, this word came from English. At least as far back as 1958, it appeared in newspapers (매일신문 1958a, 1958b), including one (1958a) that seems to be decrying Korean women taking up Western clothing trends, although I’m not totally sure due to the old-fashioned language. In these pieces, unlike in more recent ones, it appears in quotes, so it was probably common enough but not yet fully adopted into the Korean language.
That onepiece had entered Korean by the 1950s suggests that it came into Korean through Japanese, probably during the colonial era. A lot of other words for Western-style clothing did come into Korean this way, including rŏnning-syŏch’ŭ (런닝셔츠, or sleeveless undershirt); chamba (잠바, jumper); and waisyasyŏch’ŭ (와이셔츠, men’s dress shirt, from “white shirt”) (Ramsey 2006). It seems likely that onepiece came over in company with these words.
In any case, now it’s totally embedded in the language, and any previous words for dress have disappeared from daily use.
Onepiece usually refers to a cute, casual-style dress, or possibly office wear, not formalwear. And Korean norms dictate different cuts than Western ones: Shoulders covered, higher necklines, but much shorter hems. The shoulders thing is starting to change, but it’s still, I think, considered a bit risqué for anything other than nightlife or the beach. And in South Korea, where femininity is played up a lot more than in the West, the onepiece is extremely popular.
A note on spelling and romanization: McCune-Reischauer’s system would romanize 원피스 as wŏnp’isŭ; revised romanization would have it as wonpiseu. I prefer to use English spellings for English-derived words in this blog because it makes it easier for most people to read.
Ramsey, S. Robert. 2006. “Korean in Contact with Japanese.” Korean Language in Culture and Society. ed. Ho-min Sohn. pp. 57-62. Honolulu: University of Hawaii Press.
매일신문 (1958a). “每日春秋.” 매일신문. 1958년7월30일. KINDS. 2016년8월15일.
매일신문 (1958b). “晩鐘이 운다.” 매일신문. 1958년7월12일. KINDS. 2016년8월15일. some kind of fiction serial?