Unimpressed or unexcited by something because you've experienced similar things so many times before.
From French blasé, past participle of blaser meaning to tire or satiate, from Dutch 'blazen' (to blow). The concept evolved to describe the sophisticated indifference of the aristocracy.
This French word perfectly expresses why a jaded traveler won't get excited about visiting yet another famous cathedral—and English speakers borrowed it because we didn't have such a perfect word for that specific attitude!
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