unpredictable
Americanadjective
noun
adjective
Other Word Forms
Etymology
Origin of unpredictable
First recorded in 1855–60; un- 1 + predictable
Explanation
When something's unpredictable, it doesn't happen at expected times or it can't be predicted. If trains were unpredictable, they wouldn't follow a set schedule and you'd never know when one would arrive. The adjective unpredictable can also describe something that's unexpected or not known in advance. Your soccer team's skill level might be wildly unpredictable — from game to game your coach never knows what you guys will do. It can be an insult if someone calls you an unpredictable person. That means people can't rely on you for things, such as consistently good work or keeping your promises.
Vocabulary lists containing unpredictable
Power Prefix: un-
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Speak
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Twenty Thousand Leagues Under the Sea
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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.
Unpredictable rainfall and shifting humidity levels proved to be the biggest obstacles to SAI's success.
From Science Daily • Nov. 4, 2025
Unpredictable meal times and lack of washroom facilities or changing rooms for women on some trains added to the challenges.
From BBC • Oct. 3, 2025
Unpredictable and accelerated land movement prompted power shutoffs in Rancho Palos Verdes.
From Los Angeles Times • Sep. 5, 2024
An Unpredictable Storm Season: The rhythms of South Florida’s rainy season used to be somewhat predictable, with hot, humid days leading to midafternoon thunderstorms and then clear skies.
From New York Times • Jun. 15, 2024
“Well, Noah, you’ve got to admit,” Miles Umlatt said, “his behavior has been erratic. Unpredictable, I mean.”
From "Flush" by Carl Hiaasen
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.
