In a manner that is bothersome, annoying, or causing trouble; irritatingly or inconveniently.
From 'bothersome' (adjective meaning annoying) plus the adverbial suffix '-ly,' which transforms adjectives into adverbs describing how actions are performed or how things are done.
This adverb stack—'bother' + 'some' (to make an adjective) + 'ly' (to make an adverb)—shows how English builds longer words by adding suffixes one at a time, like stacking blocks!
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