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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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 weather is leading to more boats capsizing, especially small fishing vessels that are going further out and are not built for such long, rough trips," he told the BBC.
From BBC • Oct. 23, 2025
Unpredictable winds and dry fuels are creating challenges for firefighters struggling to slow a 70,000-acre wildfire that started in California’s Mojave National Preserve and spread across the state border Sunday afternoon into Nevada.
From Los Angeles Times • Jul. 30, 2023
Unpredictable public transport delays and cancellations get the worker bee in trouble with her snooty boss and septuagenarian nanny, while taxi rides that cost triple the rate of a regular ride drain her bank account.
From New York Times • Feb. 2, 2023
Unpredictable severe droughts last for years, punctuated by equally unpredictable torrential rains and floods.
From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond
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.
