unpredictable
Americanadjective
noun
adjective
Other Word Forms
- unpredictability noun
- unpredictableness noun
- unpredictably adverb
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.
Studying dense crowds is difficult because individuals can take countless possible paths and interact in unpredictable ways, Liu explained.
From Science Daily • Apr. 15, 2026
But the length of the current conflict is unpredictable, and could yet trigger stress through “channels not yet fully apparent.”
From Barron's • Apr. 14, 2026
A real strike on civilization as we know it occurred in Silicon Valley, where a new AI super-brain was locked up because it’s too powerful — and unpredictable.
From Los Angeles Times • Apr. 14, 2026
One of the largest and traditionally unpredictable costs is labor.
From The Wall Street Journal • Apr. 10, 2026
Weather unpredictable but it’s the last chance before we lose the November moon.
From "Code Name Verity" by Elizabeth Wein
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.
