In the manner of fasting; while abstaining from food, or in a way characteristic of someone who is fasting.
From 'fasting' (the present participle/gerund of 'fast') plus '-ly,' creating an adverb describing an action done during or as if during a fast.
You might say someone spoke fastingly—with the weakened voice and deliberate slowness of someone who hasn't eaten—it's a wonderfully specific adverb for capturing a physical state!
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