Happening or arriving without warning or prior notification to others.
From the prefix 'un-' (not) + 'announced' (from Latin 'annuntiare' meaning 'to make known'). The compound word became common in English by the 1600s.
There's something delightfully paradoxical about the word 'unannounced'—the very act of saying it 'announces' something that was supposed to be secret!
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