The term "unslakeable" is often used to describe a boundless or insatiable thirst or desire. Synonyms for this word include unquenchable, insatiable, insatiate, unappeasable, and ravenous. These words all describe a deep craving or longing that cannot be satisfied, no matter how much is provided or consumed. "Unsatisfied" and "never-ending" can also be used to describe this state of constant yearning. In literature, this type of longing is often representative of a character's inner turmoil and desire for something greater than themselves. It evokes a sense of restlessness and unease that propels the story forward.