In a manner full of grief or deep sorrow; mournfully and with sadness.
From 'griefful' plus the adverb suffix '-ly,' creating an adverbial form that modifies verbs or adjectives to show the manner of action.
The stacking of suffixes here shows how English builds words—'grief' (noun) + '-ful' (adjective suffix) + '-ly' (adverb suffix) = a word that describes how something is done with deep sadness.
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