suffix, occurring in adjs., is chiefly f. L. -e-us + -OUS. The Eng. words with this suffix are for the most part practically mere adaptations of L. adjs. in -eus, the senses of which they generally retain. While, however, the L. adjs. in -eus f. sbs. denoting material substances have usually the sense ‘composed of,’ as well as the sense ‘of the nature of, resembling,’ their Eng. derivatives in -eous express the latter meaning only: compare, e.g., argenteous, ligneous, vitreous, with the corresponding words in Latin. In a very few cases (e.g., aqueous) Eng. adjs. in -eous have been formed directly on L. sbs. The L. ending -eus also occurs as part of a complex suffix, as in the words in -āceus (see -ACEOUS) and -āneus (cf. consentaneous, instantaneous).
2. In beauteous, bounteous, duteous, plenteous, the ending -eous arises from the addition of the suffix -ous to -te, earlier form of -TY; but in the older words of this formation -teous replaces an earlier -tivous, f. Fr. -tif + -OUS; e.g., bounteous was originally bountivous, f. Fr. bontif, f. bonté: see BOUNTY.
3. In a few instances -eous is an analogical deformation of other suffixes, as in righteous (for rightwise), courteous, for ME. curteis a. OFr. curteis (-eis:—L. -ēnsem).
