frown

Short definition from Wiktionary

Noun

1. 1
   A wrinkling of the forehead with the eyebrows brought together, typically indicating displeasure, severity, or concentration.
2. 2
   A downturn of the corners of the mouth, typically expressing sadness.
3. 3
   Any facial expression that indicates disapproval or displeasure.

Verb

1. 1
   To have a frown on one's face.
2. 2
   To manifest displeasure or disapprobation; to look with disfavour or threateningly.
3. 3
   To repress or repel by expressing displeasure or disapproval; to rebuke with a look.
4. 4
   To communicate by frowning.