In the manner of ice; with a cold or chilling effect. (adverb)
In an uncaring manner. (adverb)
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Use "icily" in a sentence
""He calls himself the Talon," Louise said, eyeing him icily."
"As icily controlling as Agnes, with the sweet superficiality that keeps suburban women from instantly attacking each other, Edna is a manipulative bitch with a false sense of dignity and entitlement."
""You surely don't mean to say that Mr. Hapgood is stupid?" she demanded icily."