1788, "of or pertaining to (ancient) Persia," from Iran + -ian. From 1839 in reference to the language. As a noun, "an inhabitant of Persia" (1792), later "the language of Persia" (1850). Iranic (adj.) is from 1847.
ipso facto
ir-
Ira
iracund
Iran
Iranian
Iraq
irascibility
irascible
irate
ire