IPA: /ˈfrɔːstɪli/
KK: /ˈfrɔstɪli/
In a manner that is cold or unfriendly, often showing a lack of warmth or enthusiasm.
She responded frostily to his compliment, making it clear she was not interested.
Frostily → It is formed from "frost" (from Old English *forst*, meaning frozen dew or ice) and "-ily" (meaning in a manner of). The word "frostily" means in a manner that is cold or unfriendly, akin to frost.
Think of the word 'frost' which evokes a sense of coldness, and remember that 'frostily' describes behaving in a cold or unfriendly manner.