Definition of gas noun from the Oxford Advanced American Dictionary

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gas

noun
/ɡæs/
 
 
plural gases or less frequent gasses

in vehicle

1 (also gasoline) [uncountable] a liquid obtained from petroleum, used as fuel in car engines, etc.We need to stop for gas.a gas stationa gas pumpto fill up the gas tank2 the gas [singular] = gas pedalStep on the gas, we're late.

not solid/liquid

3 [countable, uncountable] any substance like air that is neither a solid nor a liquid; for example, hydrogen and oxygen are both gasesAir is a mixture of gases.CFC gasesa gas bottle/cylinder (= for storing gas) see also greenhouse gas4 [uncountable] a particular type of gas or mixture of gases used as fuel for heating and cookinga gas stove/furnacea gas explosion/leakgas heat see also coal gas, natural gas5 [uncountable] a particular type of gas used during a medical operation, to make the patient sleep or to make the pain lessan anesthetic gasDid you have gas or an injection? see also laughing gas6 [uncountable] a particular type of gas used in war to kill or injure people, or used by the police to control peoplea gas attack see also CS gas, mustard gas, nerve gas, tear gas

fun

7 [singular] a person or an event that is funThe party was a real gas.

in stomach

8 [uncountable] air that you swallow with food or drink; gas that is produced in your stomach or intestines that makes you feel uncomfortable
IDIOM

run out of gas

(informal) to lose energy and enthusiasm and stop doing something, or do it less wellrun out of gas