In an annoying or irritating manner; in a way that causes annoyance.
From annoyous + -ly (adverb-forming suffix). This creates the adverbial form of the archaic adjective 'annoyous,' following the standard English pattern for adverbs.
This word is so archaic that most modern dictionaries don't include it, yet it demonstrates the predictable, mechanical way English creates adverbs from adjectives—a system so productive you could use it to form adverbs that were never actually written down.
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