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Synonyms

doubtless

American  
[dout-lis] / ˈdaʊt lɪs /

adverb

  1. without doubt; certainly; surely; unquestionably.

  2. probably or presumably.


adjective

  1. free from doubt or uncertainty; certain, sure.

doubtless British  
/ ˈdaʊtlɪs /

adverb

  1. certainly

  2. probably

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

adjective

  1. certain; assured

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Synonym Usage

Doubtless, undoubtedly, indubitably, unquestionably are adverbs that express certainty. Doubtless, although it sometimes denotes an absolute degree of certainty, more often means “probably,” “presumably,” or “no doubt”: She will doubtless accept the offer. Undoubtedly means “beyond doubt”: undoubtedly the most prolific and popular composer of his time. Indubitably and unquestionably both affirm an unassailable conviction; they differ only in tone, indubitably being appropriate to more formal or learned discourse and unquestionably appropriate in a wider range of contexts and styles: an indubitably (or unquestionably) accurate transliteration of the hieroglyphic text; unquestionably the hottest running back in the league.

Other Word Forms

Etymology

Origin of doubtless

First recorded in 1300–50, doubtless is from the Middle English word douteles. See doubt, -less

Explanation

Use the adverb doubtless to mean "absolutely" or "without question." You could tell your brother that he'll doubtless be thrilled about the birthday present you got for him. You might rule out several neighborhoods when you're looking for a new apartment to rent, knowing they'll doubtless be too expensive for you. When she invites you to dinner, your friend might warn you about her dad's long stories, adding, "He'll doubtless tell you the one about his trip to Europe during college." Doubt is at the heart of doubtless, from the Latin dubitare, "to doubt, question, or hesitate."

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

They are the current T20 World Cup holders but were flummoxed by England's spinners and doubtless their opponents at the tournament will have taken note.

From BBC May 25, 2026

Some of it, doubtless, is personality, and some of it due to differing policy priorities.

From The Wall Street Journal May 18, 2026

That is one element of this which the committee is doubtless going to want to probe further, and perhaps where Sir Olly felt on shakiest ground.

From BBC Apr. 21, 2026

Lorne Michaels doubtless has her on speed dial.

From Los Angeles Times Mar. 23, 2026

We would doubtless think the circumstances natural and lovely.

From "Cosmos" by Carl Sagan

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