1. Concerning, or using air or other gases: At the construction site, a pneumatic drill was used for digging up the street.

The wheels of Gary's bike were equipped with pneumatic tires.
2. Relating to a woman with large breasts: The new woman's magazine was looking for a model with a pneumatic figure.
3. Descriptive of something spiritual: Jane's neighbor had pneumatic beliefs, as distinguished from body and soul.
4. Referring to something filled with air: Birds have bones that are pneumatic, which means that they are hollow and filled with air.