Unattended means left alone without anyone watching or taking care of it. When something is unattended, no one is paying attention to it or supervising it at that moment.

You might see signs at an airport warning that unattended luggage will be removed. A teacher might tell students not to leave their backpacks unattended in the hallway where someone could trip over them or take them. A pot of water left unattended on the stove could boil over and make a mess.

Something unattended isn't necessarily abandoned forever, it just means nobody is looking after it right now. A parked car is unattended when the driver walks away. A store counter is unattended when the clerk steps into the back room.

Sometimes unattended situations can be dangerous or lead to problems. An unattended campfire could spread into a wildfire. An unattended young child at a pool needs supervision.