Korean syllable 됐

됐 is part of a verb form, not a whole reply by itself. It comes from 되다 (“to become”): 되었어 contracts to 됐어, and 됐 can describe something that happened, turned out a certain way, or reached a sufficient point.

Before Hangul, Korean writers adapted Chinese characters in systems called Idu, Gugyeol, and Hyangchal to write Korean speech and grammar. Hangul was created in 1443, and its principles were published in 1446 to make Korean writing easier to learn and use. The conversational force of 됐 comes from the phrase and situation around it.

Does 됐 mean no?

No; it can accept, refuse, or stop the exchange. If someone asks, “This one?”, 됐어 can mean “That works.” After an offer of more food or help, it can mean “No thanks, I’m set.” After someone offers another explanation, it can mean “Enough; stop.”

The difference is what the speaker treats as settled: the chosen option, the food or help already offered, or the explanation they have heard. The plain ending in 됐어 is casual; 됐어요 is more polite but can still draw the same boundary.