Definition from Wiktionary, the free dictionary
put on airs
- (idiomatic) To become haughty, to assume a pretentious manner.
- 1922, Margery Williams, The Velveteen Rabbit:
- Even Timothy, the jointed wooden lion, who was made by the disabled soldiers, and should have had broader views, put on airs and pretended he was connected with Government.
become haughty, assume a haughty manner