an adjectival suffix with the meanings "composed of," "resembling, having the nature of," occurring in loanwords from Latin ( igneous; ligneous; vitreous ); also, as a semantically neutral suffix, found on adjectives of diverse origin, sometimes with corresponding nouns ending in -ty 2 ( beauteous; courteous; hideous; homogeneous; plenteous; righteous ).
[ -eus; see -OUS ]