MOUTH (3)

Mouth, v. i. 1. 1. To speak with a full, round, or loud, affected voice; to vociferate; to rant.
I'll bellow out for Rome, and for my country, And mouth at Cæsar, till I shake the senate. Addison. 2. 2. To put mouth to mouth; to kiss. Shak.
3. 3. To make grimaces, esp. in ridicule or contempt.
Well I know, when I am gone, How she mouths behind my back. Tennyson.