To change clothes; to put on different clothes or take clothes off. Can be used transitively or intransitively.
仕事から帰ってすぐに服を着替えた。
I changed my clothes as soon as I got home from work.
試着室で何度か着替えてサイズを確かめた。
I tried on several outfits in the fitting room to check the size.
汗をかいたので早く着替えたい。
I want to change quickly because I'm sweaty.