-arious, suffix
forming adjs.;
1. f. L. -ārius, -a, -um ‘connected with, pertaining to’ + -ous (as if ad. L. -āriōsus; cf. cariōsus, carious). The reg. Eng. repr. of -ārius is -ary1; but the compound suffix is of occasional use, as in cibarious, gregarious, temerarious, vicarious, and as a by-form in arbitrarious, contrarious, etc. (Hilarious, f. L. hilari-s + -ous, seems to owe its form to association with this suffix.)