In a manner showing that one is displeased or annoyed.
From displeased (past participle of displease) plus the adverb suffix -ly, which turns adjectives into adverbs. This shows the productive nature of English word-building.
Adding '-ly' to any adjective to make an adverb works so well in English that we can instantly understand 'displeasedly' even if we've never seen it before—our brains are amazing word-prediction machines!
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