What it means
もう means “already” when it comes before an affirmative predicate, showing that an action has been completed or a situation is true earlier than expected. Before a negative predicate, it means “no longer” or “not anymore.” It usually comes before the main predicate, and the predicate itself changes for familiar or polite speech.
Usage note
Do not confuse もう with まだ, which means “still” or “not yet.” The expression もういい can also mean “That is enough” or “It is okay now,” depending on the context.
How to use it
私はもう食べました。
I have already eaten.
私はもうその店へ行きません。
I will not go to that store anymore.
私はもう食べた。
I have already eaten.
私はもうその店へ行かない。
I will not go to that store anymore.
Example sentences
母はもう夕食を作りました。
My mother has already made dinner.
駅の売店はもう閉まりました。
The station kiosk has already closed.
私はもう宿題を終えました。
I have already finished my homework.
図書館の本をもう返しました。
I have already returned the library book.