[1885–90; kerato- + -genous]This word is first recorded in the period 1885–90. Other words that entered Englishat around the same time include: foregut, roller coaster, sensitization, twofer, upsweep-genous is a suffix of adjectives corresponding to nouns with stems in -gen. Other words that use the affix -genous include: ectogenous, endogenous, hematogenous, heterogenous, pleurogenous