Webster's 1913 Dictionary
IRIDACEOUS; IRIDEOUS
Ir `i *da "ceous, I *rid "e *ous, a. Etym: [From NL. Iris, Iridis, the Iris. ] (Bot. )
Defn: Pertaining to, or resembling, a large natural order of endogenous plants (Iridaceæ ), which includes the genera Iris, Ixia, Crocus, Gladiolus, and many others.
New American Oxford Dictionary
iridaceous
ir i da ceous |ˌiriˈdāSHəs ˈˌɪrəˈˌdeɪʃəs | ▶adjective Botany of, relating to, or denoting plants of the iris family (Iridaceae ), which grow from bulbs, corms, or rhizomes. ORIGIN mid 19th cent.: from modern Latin Iridaceae (plural ), based on Greek iris, irid- ‘rainbow, ’ + -ous .
Oxford Dictionary
iridaceous
iridaceous |ˌʌɪrɪˈdeɪʃəs, ˌɪrɪ -| ▶adjective Botany relating to or denoting plants of the iris family (Iridaceae ), which grow from bulbs, corms, or rhizomes. ORIGIN mid 19th cent.: from modern Latin Iridaceae (plural ), based on Greek iris, irid- ‘rainbow ’, + -ous .
The Wordsmith Dictionary