undoubtedly

undoubtedly — adverb

1. a word used to show that you are completely certain about what you are saying —

1.adverbB2
Definition

a word used to show that you are completely certain about what you are saying — for example, saying that a candidate is undoubtedly the best choice, or that a problem will undoubtedly get worse without action.

Example

Bao is undoubtedly the best person for this new role.

undoubtedly + complement phrase

The documentary about sea turtles was undoubtedly the most popular programme this month.

undoubtedly between verb and complement

Common collocations
  • undoubtedly true
  • undoubtedly correct
  • undoubtedly the best
  • undoubtedly one of
  • will undoubtedly
Synonyms
  • certainly

    the most neutral and frequent equivalent in both speech and writing

  • definitely

    more common in casual conversation; slightly less formal than 'undoubtedly'

  • unquestionably

    more formal, often used in academic or professional analysis

  • assuredly

    rare in modern English; mostly appears in literary or very formal texts

Antonyms
  • doubtfully

    expressing uncertainty rather than certainty

  • questionably

    suggesting that the truth of the statement is open to challenge

Grammar Patterns

undoubtedly + clause

undoubtedly before main verb

Usage Note

Sentence adverb — it modifies the whole clause, not a single word. In everyday conversation, 'definitely' or 'for sure' are more common alternatives.

Common Mistakes

She is a undoubtedly talented singer.
She is undoubtedly a talented singer.
'undoubtedly' is an adverb, so it goes before the article 'a', not after it.
That is an undoubtedly fact.
That is an undoubted fact.
before a noun, use the adjective 'undoubted' instead.

Word family

Synonym discussion

Sense: adverb/1

All four adverbs express strong certainty, but they differ in formality and context. 'Undoubtedly' is common in both speech and writing, carrying the nuance that no reasonable person could disagree. 'Certainly' is the most frequent and neutral option across all registers. 'Definitely' is the most casual and suits everyday conversation well. 'Unquestionably' is more formal than 'undoubtedly' and often used in academic or professional writing. 'Assuredly' is rare in modern English and appears mostly in literary or very formal texts. For example: 'The data is undoubtedly correct' (confident assertion), versus 'The data is definitely correct' (personal conviction), versus 'The results are unquestionably significant' (formal judgement).

certainly ↗definitely ↗unquestionablyassuredly

Common collocations

Phrases

  • there is undoubtedly
  • undoubtedly the best

Etymology

LatinOld FrenchEnglish

Formed by adding the adverb suffix '-ly' to the adjective 'undoubted', which itself combines the prefix 'un-' (not) with the past participle of 'doubt'. The verb 'doubt' entered Middle English from Old French 'douter', which comes from Latin 'dubitare' (to hesitate, be uncertain). So the word literally means 'in a manner that is not doubted'.