unintendedly

Unintendedly is an adverb formed from the adjective unintended with the suffix -ly. It denotes performing an action in an unplanned or undesired way. In modern English, unintendedly is uncommon and often regarded as nonstandard or archaic. The preferred adverb for most contexts is unintentionally, while unintended already serves as an adjective.

Etymology: The word is built from un- (not) + intended (planned or meant) and the adverbial suffix -ly, yielding “in an unplanned manner.” The base adjective unintended appears in phrases such as unintended consequences, where the emphasis is on the outcome rather than the manner of doing something.

Usage notes: Writers normally use unintentionally to modify verbs, and unintended to describe outcomes or actions that were not planned. For example: “The engineer unintentionally caused a delay,” or “The policy change led to unintended consequences.” Relative to many style guides, unintendedly would be considered rare or old-fashioned; some dictionaries mark it as a rare variant or obsolete.

Conclusion: While technically formed by standard morphemes, unintendedly is rarely used in contemporary English. For clarity and idiomatic precision, prefer unintentionally or unintended depending on whether you need an adverb or an adjective.