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-ious

American  

  1. variant of -ous, added to stems of Latin origin, often with corresponding nouns ending in -ity: atrocious; hilarious.

-ious British  

suffix

  1. characterized by or full of Compare -eous

    ambitious

    religious

    suspicious
"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of -ious

Middle English ≪ Latin -iōsus ( -i-, -ose 1 ) and Latin -ius (masculine singular adj. ending, as in varius )

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.