hear, usually without the knowledge of the speakers; "We overheard the conversation at the next table"
To hear more of (anything) than was intended to be heard; to hear by accident or artifice
If you overhear someone, you hear what they are saying when they are not talking to you and they do not know that you are listening. I overheard two doctors discussing my case. to accidentally hear what other people are saying, when they do not know that you have heard