1. Literally, to remain near or next to someone or something. Make sure you stay by Mom while we're in the airport. We don't want you getting lost! Please stay by your vehicle until emergency services arrive. I've been staying by my phone all day in case the doctor calls with the test results.

2. To remain loyal to, committed to, or supportive of someone or something. I know you and Sarah haven't been getting along recently, but I think you should stay by her for the sake of the kids. I'm staying by my decision to sell the company.