Synonyms for Unquenchable:

adj.

gluttonous (adjective)
insatiable, greedy, piggy.
insatiable (adjective)
insatiate, gluttonous, quenchless.

n.

light, greedy, full, someone's eyes are bigger than their stomach, stuffed, voracious, piggy, replete, gluttonous. unquenchable (noun)
unsatiable, insatiable, quenchless, insatiate.

Other synonyms:

gluttonous. replete, greedy, voracious. piggy. stuffed. light. Other relevant words:
greedy, voracious, replete, stuffed, gluttonous.

Usage examples for unquenchable

  1. Gasping, blinded, the others scattered; and for the third time- while the room now glowed with this unquenchable blossoming of flame- Grantham shot. – The Air Trust by George Allan England
  2. There being no witnesses of what he had said, the Senate decided to send for the boy, and when they saw how he blushed and wept with a modesty mingled with unquenchable rage, they, without requiring any other proof, found Capitolinus guilty, and condemned him to pay a fine, with which Marcellus had silver libation vessels made, and consecrated them to the gods. – Plutarch's Lives, Volume II by Aubrey Stewart & George Long
  3. The chief horror of it, from the Crusaders' point of view, was that it was unquenchable – Kelly Miller's History of the World War for Human Rights by Kelly Miller