1. the state of matter distinguished from the solid and liquid states by: relatively low density and viscosity; relatively great expansion and contraction with changes in pressure and temperature; the ability to diffuse readily; and the spontaneous tendenc
2. a fluid in the gaseous state having neither independent shape nor volume and being able to expand indefinitely
3. a volatile flammable mixture of hydrocarbons (hexane and heptane and octane etc.) derived from petroleum; used mainly as a fuel in internal-combustion engines
4. a state of excessive gas in the alimentary canal
5. a pedal that controls the throttle valve;
"he stepped on the gas"
6. a fossil fuel in the gaseous state; used for cooking and heating homes