In a manner that provides comfort, consolation, or reassurance; in a soothing or calming way.
From 'comforting' (present participle of 'comfort,' from Latin 'confortare': strengthen) + '-ly' adverb suffix. A standard modern formation showing how an action brings comfort.
The adverb 'comfortingly' is interesting because '-ingly' adverbs let us describe the emotional effect of something—'he spoke comfortingly' means his tone did the comforting, not just his words.
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