違う
chigau
“that’s wrong; different.”
違うis used to correct another person’s incorrect supposition. In most cases, you should use the desu-masu-tai form of this verb. Otherwise, you risk sounding a bit too abrupt.
A:この靴下は木綿ですか。
B:違います。ナイロンです。
A: Kono kutsushita wa momen desu ka.
B: Chigaimasu. Nairon desu.
A: Are these socks cotton?
B: No; they’re nylon.