Flatter

To praise someone excessively or insincerely, often to gain favor or advantage.

From Old French 'flater,' meaning 'to stroke with the hand' or 'to caress,' which came from a Frankish word meaning 'to stroke smoothly.' Originally, it was a literal physical action — like petting an animal to calm it. The metaphorical meaning of 'stroking someone's ego' with smooth words developed because the verbal action was seen as similar to the physical stroking. The connection between physical smoothing and verbal smoothing gave us both meanings.