In a creepy manner; in a way that is eerie, unsettling, or causes discomfort.
Adverb formed from 'creepy' with the suffix '-ly' (from Old English, transforming adjectives into adverbs indicating manner or state).
Horror movies exploit our understanding of what moves 'creepily'—slow, unpredictable movements trigger fear more effectively than fast ones because our brains can't predict where the threat will go!
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