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
His partner had somehow offended Evelyn, and though she was now disposed to forgive him, the recollection of his suppositious iniquity might afterwards rankle in her mind.
From The Protector by Harold Bindloss
But if the suppositious stranger were led to study the men a little more closely, he would be tempted to correct his first impression.
From The Duke's Motto A Melodrama by Justin H. (Justin Huntly) McCarthy
Bakahenzie, or even Mungongo, would cheerfully sacrifice him if either imagined that the damned Unmentionable One desired it, at the suppositious bidding of something which was nothing.
From Witch-Doctors by Charles Beadle
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.
