An autograph or signature (e.g., a person's written name on a document or for a fan).
コンサートで好きな歌手にサインをもらった。
I got an autograph from my favorite singer at the concert.
契約書には必ずサインをしてください。
Please be sure to sign the contract.
彼のサインは独特で、すぐに誰のものか分かる。
His signature is distinctive; you can tell whose it is immediately.
A sign or signal; an indication or cue that something is happening or should happen.
彼がうなずいたのが出発のサインだった。
His nod was the signal to depart.
株価の動きは景気回復のサインかもしれない。
The stock movement might be a sign of an economic recovery.
観客の反応が次の演出に移るサインだ。
The audience's reaction was the cue to move on to the next performance.