In a coy manner; in a way that is playfully shy or evasively modest.
From 'coy' plus the adverb-forming suffix '-ly'. The root 'coy' comes from Old French 'coi' (quiet).
When you add '-ly' to an adjective, you get an adverb describing how something is done—'coyly' is how someone acts when they're being playfully modest, often tilting their head or looking away just a bit.
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