A particle meaning 'too', 'also', or 'as well'. In negative sentences it can mean 'not ... either'.
私も行きます。
I'll go too.
彼も来ないなら、私も行かない。
If he isn't coming either, I won't go either.
コーヒーもください。
Please give me a coffee as well.
Used in the pattern 'AもBも' to mean 'both A and B' or, in a negative sentence, 'neither A nor B'.
日本語も英語も話せます。
I can speak both Japanese and English.
映画も音楽も興味がない。
I'm not interested in either movies or music.
Used to emphasize quantity or degree (e.g., 'even', 'as many as', 'no fewer than'). It often stresses that the amount is surprisingly large or notable.
彼は三回も失敗した。
He failed three times (as many as three times).
1時間も待ったのに来なかった。
I waited for as long as an hour, but they didn't come.
Used to express concession or hypothetical meaning like 'even if' or 'even though' (often seen in forms like 〜ても, 〜でも, 〜とも).
雨でも行きます。
I'll go even if it rains.
忙しくても、連絡してください。
Even if you're busy, please contact me.
A colloquial adverbial use meaning 'more', 'again', 'another' — related to もう (mou). This is informal and appears in casual speech.
も一回やってくれない？
Can you do it one more time?
疲れたから、も休憩しよう。
I'm tired, so let's rest a bit more.