[ uhn-sur-tn ]
See synonyms for uncertain on Thesaurus.com
  1. not definitely ascertainable or fixed, as in time of occurrence, number, dimensions, or quality.

  2. not confident, assured, or free from hesitancy: an uncertain smile.

  1. not clearly or precisely determined; indefinite; unknown: a manuscript of uncertain origin.

  2. vague; indistinct; not perfectly apprehended: an abstruse novel with uncertain themes.

  3. subject to change; variable; capricious; unstable: a person of uncertain opinions.

  4. ambiguous; unreliable; undependable: Her loyalties are uncertain.

  5. dependent on chance or unpredictable factors; doubtful; of unforeseeable outcome or effect.

  6. unsteady or flickering, as light; of changing intensity or quality.

Origin of uncertain

First recorded in 1250–1300; Middle English; un-1 + certain

synonym study For uncertain

1. Uncertain, insecure, precarious imply a lack of predictability. That which is uncertain is doubtful or problematical; it often involves danger through an inability to predict or to place confidence in the unknown: The time of his arrival is uncertain. That which is insecure is not firm, stable, reliable, or safe, and hence is likely to give way, fail, or be overcome: an insecure foundation, footing, protection. Precarious suggests great susceptibility to failure, or exposure to imminent danger: a precarious means of existence.

Other words for uncertain

Other words from uncertain

  • un·cer·tain·ly, adverb
  • un·cer·tain·ness, noun

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use uncertain in a sentence

  • And the Ukrainian army, slowly, uncertainly, but ineluctably, is closing in on this besieged ghost-town of a city.

  • He seemed so at ease with the people there, and they with him, that I asked uncertainly where he came from.

    The Case for Cardinal Sean O’Malley | Christopher Dickey | March 12, 2013 | THE DAILY BEAST
  • The result was an extra month of uncertainly that impeded an already volatile hiring market.

    Obama’s Jobs Malaise | Daniel Stone | September 2, 2011 | THE DAILY BEAST
  • When her husband died in a suicide, she stumbled uncertainly at first.

    Caroline: The Reasons Why | Tina Brown | January 5, 2009 | THE DAILY BEAST
  • “Everybody brags on being the most aggrieved,” the mayor explained as he settled uncertainly onto the edge of the sofa table.

    The Way the Wind Blows | Scott Simon | December 21, 2008 | THE DAILY BEAST
  • When they reached the house Betty started to knock, then paused uncertainly, her hand uplifted.

  • Muttering curses, and swaying uncertainly on his feet, Talpers seized his hat and rushed from the house.

    Mystery Ranch | Arthur Chapman
  • The answer seemed to break up the order of his prearranged consolations, and he sat looking at her uncertainly.

    Summer | Edith Wharton
  • Someone thrust her out of the door with others, and she began to step aimlessly, uncertainly, along the broad street.

    Blazed Trail Stories | Stewart Edward White
  • He assumed the upright posture, and standing uncertainly for a few seconds, fixed his eyes on the prisoner.

    The Young Ranchers | Edward S. Ellis

British Dictionary definitions for uncertain


/ (ʌnˈsɜːtən) /

  1. not able to be accurately known or predicted: the issue is uncertain

  2. (when postpositive, often foll by of) not sure or confident (about): a man of uncertain opinion

  1. not precisely determined, established, or decided: uncertain plans

  2. not to be depended upon; unreliable: an uncertain vote

  3. liable to variation; changeable: the weather is uncertain

  4. in no uncertain terms

    • unambiguously

    • forcefully

Derived forms of uncertain

  • uncertainly, adverb
  • uncertainness, 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

Other Idioms and Phrases with uncertain


see in no uncertain terms.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.