pneu·mat·ic / n(y)oōˈmatik/ • adj. 1. containing or operated by air or gas under pressure. ∎ Zool. (chiefly of cavities in the bones of birds) containing air. ∎ inf. (of certain body parts, esp. a woman’s breasts) large, as if inflated: she’s the one with the pneumatic lips and breasts. ∎ inf. (of a woman) having large breasts: Lee and his pneumatic wife.2. of or relating to the spirit.• n. (usu. pneumatics) an item of pneumatic equipment.DERIVATIVES: pneu·mat·i·cal·ly / n(y)oōˈmadək(ə)lē/ adv.pneu·ma·tic·i·ty / ˌn(y)oōməˈtisədē/ n.