To be wary means to be careful and alert because you sense possible danger or problems ahead. When you're wary of something, you don't rush in blindly: you watch closely, think carefully, and stay ready to protect yourself.

A deer in the forest is wary of sudden noises. A student might be wary of a “too good to be true” offer from a classmate. You might feel wary about trying a new food that looks strange, or wary of a dog you don't know, even if someone says it's friendly.

Being wary isn't the same as being afraid. Fear makes you want to run away. Wariness makes you cautious and observant. A wary person pays attention, asks questions, and doesn't assume everything will work out perfectly. If your friend suggests a shortcut through an unfamiliar neighborhood, a wary response would be to think it through first rather than automatically following.

The phrase “once bitten, twice shy” captures the spirit of wariness: after you've been tricked or hurt once, you become wary in similar situations. Smart people stay wary of things that seem suspicious or risky, which helps them avoid trouble that careless people walk right into.