Somewhat coy; having qualities of being shy or evasive in a mild way.
From 'coy' plus the suffix '-ish' (meaning somewhat or having the quality of). This creates an adjective meaning 'somewhat coy' or 'coy-like'.
The '-ish' suffix is English's way of saying 'kind of'—adding it to adjectives makes them softer and less absolute, so 'coyish' means someone's acting a little bit coy rather than fully coy.
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