Mammoth Uncensored Word List:
54 - 4 letter words starting with i

ibex ibis iced icer ices ichs icky icon idea ides idle idly idol idyl iffy iggs iglu ikon ilea ilka ilks ills illy imam immy impi imps inby inch ingo inks inky inly inns inro inti into ions iota ired ires irid iris irks iron isba isit isle isms isos itch item iwis ixia