mistakenly

IPA/mɪˈsteɪkənli/
KK[mɪstˈekənli]IPA/mɪˈsteɪkənli/

mistakenly — adverb

1. because of an incorrect belief, a wrong judgement, or an unintended action — not

1.adverbB1
Definition

because of an incorrect belief, a wrong judgement, or an unintended action — not because the person meant to be wrong

Example

Tara mistakenly poured salt into her coffee instead of sugar at breakfast.

mistakenly + action verb describing an unintended physical error

The library staff mistakenly believed that the rare book had been returned last Tuesday.

collocation: mistakenly believe / assume / think (cognitive verbs)

Common collocations
  • mistakenly believe
  • mistakenly assume
  • mistakenly think
  • mistakenly identify
  • mistakenly assume that
  • widely / commonly mistakenly believed
Synonyms
  • wrongly

    broader; can also mean 'in a way that is morally wrong', while 'mistakenly' focuses on factual error or unintended action

  • erroneously

    more formal; common in academic, legal, or technical writing

  • incorrectly

    narrower; usually about answers, procedures, or results being inaccurate rather than beliefs

  • inadvertently

    emphasises lack of intention more than the error itself; useful when the action was unintentional rather than based on a wrong belief

Antonyms
  • correctly

    the most direct opposite when the action or belief turns out to be right

  • deliberately

    opposite in intent — done on purpose rather than by error or accident

  • intentionally

    opposite in intent; pairs with the same verbs (assumed, identified, sent)

Grammar Patterns

mistakenly + verb

mistakenly believe / assume / think / identify

Usage Note

Frequently modifies cognitive verbs (believe, assume, think, identify) when the speaker wants to mark that the belief or recognition turned out to be wrong; also pairs with action verbs (send, take, pour) for unintended physical errors. Position is typically before the main verb.

Common Mistakes

He acted mistakenly to the news.
He mistakenly reacted to the news as if it were urgent.
'mistakenly' modifies the verb describing the wrong action; it does not stand alone after a verb like 'acted'.
The decision was mistakenly.
The decision was made mistakenly.' or 'The decision was wrong.
'mistakenly' is an adverb, not an adjective; pair it with a verb, not a linking 'be'.

Word family

Synonym discussion

Sense: adverb/1

All five adverbs describe an action or belief that turns out to be not right, but they part ways on what kind of 'not right' is meant. 'Mistakenly' focuses on a factual error or an unintended action and is the most neutral everyday choice; it pairs naturally with cognitive verbs (believe, assume, identify) and with quick physical slips (sent, took, poured). 'Wrongly' is broader — it can describe a moral wrong as well as a factual one, as in 'wrongly accused'. 'Erroneously' is more formal and is favoured in legal or academic writing. 'Incorrectly' usually attaches to procedures, calculations, or answers ('answered incorrectly'). 'Inadvertently' shifts the spotlight to the lack of intention rather than the error itself, so 'she inadvertently insulted him' implies no malice but does not necessarily mean she was acting on a wrong belief.

mistakenly ↗wrongly ↗erroneously ↗inadvertently ↗incorrectly ↗

Common collocations

Adverbs

Phrases

  • mistakenly believe that
  • mistakenly assume that
  • be mistakenly identified as

Prepositions

Etymology

Old NorseMiddle EnglishEnglish

Built from the adjective 'mistaken' plus the adverb-forming suffix '-ly'. 'Mistaken' itself is the past participle of the verb 'mistake', which entered English in the 14th century from Old Norse 'mistaka' — literally 'to take in error', from 'mis-' (wrongly) + 'taka' (to take). The modern adverb thus carries the original idea of taking or doing something in the wrong way.