adverb Also doubt·less·ly.

without doubt; certainly; surely; unquestionably.
probably or presumably.


free from doubt or uncertainty; certain, sure.

Origin of doubtless

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

Synonym study

1, 2. 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. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for doubtlessly

Contemporary Examples of doubtlessly

Historical Examples of doubtlessly

  • Some of us must doubtlessly perish spiritually in such investigations.

  • Lorenzo slain, too, and doubtlessly also by the impetuous Viscount's hand!

  • This also must doubtlessly be rejected, as Haberlandt has observed.

  • Besides, consciously or unconsciously, you have doubtlessly encouraged Wilson.

    The Day of Judgment

    Joseph Hocking

  • They doubtlessly intended to camp for a portion of the night at this spot.

    The Trail-Hunter

    Gustave Aimard

British Dictionary definitions for doubtlessly


adverb Also: doubtlessly (sentence substitute or sentence modifier)



certain; assured
Derived Formsdoubtlessness, noun
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

Word Origin and History for doubtlessly


mid-14c. (adv.), mid-15c. (adj.), from doubt (n.) + -less. Related: Doubtlessly.

Online Etymology Dictionary, © 2010 Douglas Harper