-eoussuff. Having the nature of; resembling: gaseous.[Middle English, from Old French -eux, -eus (from Latin -?sus) and from Latin -eus.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.-eous suffix forming adjectives relating to or having the nature of: gaseous. Compare -ious [from Latin -eus]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014-eous an adjectival suffix with the meanings ?composed of,? ?resembling, having the nature of,? occurring in loanwords from Latin (igneous; vitreous); also, as a semantically neutral suffix, found on adjectives of diverse origin, sometimes with corresponding nouns ending in -ty2 (beauteous; courteous; homogeneous). [