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-
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Speak
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Twenty Thousand Leagues Under the Sea
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
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.
One reason is courts in states like Delaware and New Jersey have become unpredictable.
From The Wall Street Journal • May 18, 2026
The misoprostol-only protocol has some downsides: It can be a bit more unpredictable, since it can take longer for a body to expel a pregnancy if it’s not prepped with mifepristone.
From Slate • May 18, 2026
“Her travel patterns continue to demonstrate the unpredictable movements of a dispersing wolf seeking a mate and territory of its own,” John Marchwick, of the educational group California Wolf Watch, said in a statement.
From Los Angeles Times • May 18, 2026
Beyond diplomatic niceties and behind closed doors, Beijing will be looking for small, concrete achievements, analysts said, but will stay "realistically pragmatic" given Trump's unpredictable nature.
From Barron's • May 8, 2026
Though I doubted my fate would be so drastic, the man was unpredictable.
From "The Shakespeare Stealer" by Gary L. Blackwood
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.
