suppositious
Americanadjective
Other Word Forms
Etymology
Origin of suppositious
First recorded in 1615–25; shortened form of supposititious
Explanation
Something you assume to be true without having any real proof is suppositious. If there's no evidence that your brother stole your favorite sweatshirt, it's suppositious to accuse him of the deed. When you use supposition, or an unproven belief, to decide something, that's suppositious. Both words come from suppose and its root, which means "to assume." This adjective is uncommon today — you're more likely to say "unfounded" or "based on an assumption." Still, feel free to pull out suppositious for situations such as the suppositious evidence a substitute teacher uses to punish the whole class for passing notes.
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.
In a year when snooker's maximum break, once considered as suppositious as the Himalayan Yeti, has repeatedly shown up for the cameras, it fell to O'Sullivan to show that nobody does it better.
From BBC ● Dec. 2, 2025
By quotations from suppositious, always unnamed "authorities," by innuendoes and by skilled selection of facts he presumed to prove hat Henry Ford is decaying as a maker of motor cars.
From Time Magazine Archive
The indication in the story that the device for annulling Constance’s marriage proceeded from Joan is suppositious, but by no means improbable.
From The White Rose of Langley A Story of the Olden Time by Holt, Emily Sarah
The example may be either actual or suppositious, but it must illustrate clearly and accurately.
From Public Speaking by Stratton, Clarence
For examples of the two methods let us consider suppositious cases.
From Certain Success by Hawkins, Norval A.
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.
