Describes a want, a need, or a feeling that can never be filled up — however much you get, you still want more. It is used most about desire, thirst, hunger, curiosity, ambition, anger, and love: an unquenchable thirst for knowledge, an unquenchable desire to win. The word comes from thirst: to quench a thirst is to end it by drinking. So the picture is of drinking and drinking and still being thirsty. That is why the strongest and most natural partner word is 'thirst', and 'unquenchable thirst for...' is close to a set phrase. It is a formal, literary word. You will find it in writing, in speeches, in obituaries praising someone's endless curiosity — not usually in ordinary conversation, where people say 'he never gets enough of it' or 'she can't get enough'. Quench is also used about fire, so 'unquenchable' can describe a flame or a spirit that cannot be put out: an unquenchable fire, an unquenchable optimism. That second use is warmer and more admiring — it praises someone whose hope or energy nothing can kill. Worth knowing: whether the word sounds like praise or worry depends entirely on what follows it. Unquenchable curiosity is a compliment; unquenchable greed is not.

無法滿足的、無窮無盡的（如求知慾、渴望）；（火、意志）撲不滅的