Wiktionary
unslakable
a. That cannot be slaked
Usage examples of "unslakable".
Khorne, the Blood God, lord of slaughter, whose followers went laughing into battle filled with an unslakable thirst for carnage.
Rudy could see the overwhelming temptation to knowledge, the curiosity that amounted in the mageborn to an almost unslakable lust.
Shame and unslakable passion bound Augustus closer to her than if their mutual longings had been nightly satisfied or than if she had borne him a dozen fine children.
They do not reckon with my power over these events, nor with what unslakable desire I return to Helen.