sneer

Short definition from Wiktionary

Verb

1. 1
   To raise a corner of the upper lip slightly, especially in scorn.
2. 2
   To utter with a grimace or contemptuous expression; to say sneeringly.

Noun

1. 1
   A facial expression where one slightly raises one corner of the upper lip, generally indicating scorn.
2. 2
   A display of contempt; scorn.