The definition of gassed is slang for drunk or intoxicated, or for being out of energy.
Being drunk from drinking two bottles of wine by yourself is an example of being gassed.
A runner's feeling after running a half marathon is an example of gassed.
Gassed is defined as having killed with or exposed to poisonous gas.
Having fumigated a house to kill fleas is an example of gassed.
Drunk or intoxicated.