stand by phrasal verb ( see also ↑ stand )
1 . to not do anything to help someone or prevent something from happening ⇨ bystander :
I’m not going to stand by and see her hurt.
2 . stand by something to keep a promise, agreement etc, or to say that something is still true:
I stand by what I said earlier.
He stood by his convictions.
3 . stand by somebody to stay loyal to someone and support them, especially in a difficult situation:
His wife stood by him during his years in prison.
4 . to be ready to do something if necessary ⇨ standby :
Rescue crews were standing by in case of a breakdown.
stand by for
Stand by for our Christmas competition.
stand by to do something
Police stood by to arrest any violent fans.