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Synonyms

unpredictable

American  
[uhn-pri-dik-tuh-buhl] / ˌʌn prɪˈdɪk tə bəl /

adjective

  1. not predictable; not to be foreseen or foretold.

    an unpredictable occurrence.
    Synonyms:
    uncertain, variable, fitful, erratic

noun

  1. something that is unpredictable.

    the unpredictables of life.
unpredictable British  
/ ˌʌnprɪˈdɪktəbəl /

adjective

  1. not capable of being predicted; changeable

"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 Word Forms

  • unpredictability noun
  • unpredictableness noun
  • unpredictably adverb

Etymology

Origin of unpredictable

First recorded in 1855–60; un- 1 + predictable

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.

The triple lock creates a big but unpredictable ratchet for the government’s social-spending bill: No one can guess over time how fast old-age social spending will grow.

From The Wall Street Journal • Apr. 2, 2026

In the meantime, the biggest thing since cryptocurrency has an unpredictable future.

From Barron's • Mar. 28, 2026

High-end and low-end customers alike adored his frisky, unpredictable spirit — both on and off the runway.

From Salon • Mar. 27, 2026

Committee chair Dame Meg Hillier said it reflected modern banking's trade-off in enabling convenience but also "unpredictable errors".

From BBC • Mar. 27, 2026

With that, Lamphere's FBI career would veer off in a new and unpredictable direction.

From "Spies: The Secret Showdown Between America and Russia" by Marc Favreau

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

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