To leer means to look at someone in a creepy, unpleasant way that makes them uncomfortable. A leer is a sneaky, sideways glance that feels wrong, like someone is looking at you in a way they shouldn't.

In stories, villains often leer at heroes to show their nasty intentions. In The Lord of the Rings, the creature Gollum leers at Frodo and Sam when he's plotting something sinister. A bully might leer at a classmate they're planning to pick on, giving them a knowing, unpleasant smile that signals trouble ahead.

When someone leers, their face often shows they're thinking unkind or suspicious thoughts. It's the opposite of a friendly glance or an honest, direct look.

You might also see leer used as a noun: “He gave an unpleasant leer that made her want to leave the room.”