Leer (verb)

1. To look at someone or something with a sly or lecherous expression.
2. To look at someone or something with a sly or cunning expression.

Origin:

1590s, from middle english leren, from old english læran "to look askance," from proto-germanic *lairaz (compare old frisian lera "to leer," old high german lerren "to squint," german lächeln "to smile"), from pie *leis- "smooth, slippery" (compare latin lasus "smooth," greek leios "smooth," old church slavonic ljutu "angry").

Examples:

1. He leered at her in a suggestive manner.
2. The old man leered at the young girl.
3. He gave her a leering grin.
4. The criminal leered at the judge before being sentenced.
5. She felt uncomfortable when he leered at her.