どこ
どこ · doko · JLPT N5 · noun
where
🚪 Sounds like door-ko: which door? Where? The do- marks a question word.
Part of the ko-so-a-do set: koko (here), soko (there), asoko (over there), doko (where). The do- prefix always asks a question, as in dore (which one) and dou (how), while -ko means place.