Unquenchable (adjective)

1. Impossible to extinguish or satisfy.
2. Not able to be put out or satisfied.

Origin:

Un- + quenchable.

Examples:

1. The fire was unquenchable, consuming everything in its path.
2. His thirst was unquenchable.
3. The desire for power was unquenchable.
4. His curiosity was unquenchable.
5. The unquenchable need for revenge consumed him.