If "quench" refers to satisfying thirst:
* Induce thirst: To make someone thirsty.
* Dehydrate: To remove water from someone or something.
* Parched: Extremely thirsty.
If "quench" refers to extinguishing fire:
* Ignite: To set fire to something.
* Kindled: To start a fire.
* Fuel: To provide material that sustains a fire.
If "quench" refers to suppressing or ending something:
* Stimulate: To encourage or activate something.
* Reignite: To start again after being stopped.
* Exacerbate: To make worse.
If "quench" refers to cooling something down:
* Heat: To raise the temperature of something.
* Warm: To make something less cold.
* Inflamed: To be hot, red, and painful.
To determine the most appropriate opposite, consider the specific context in which "quench" is used.