I-de-a, meddylddrych; amgyffred
Id-i-om, ieithwedd
Id-i-ot, hurtyn, gwirionyn
I-dle-ness, segurdod, diogi
Ig-no-ble, anenwog, gwael
Ig-no-rance, anwybodaeth, annysg
Ig-no-rant, anwybodus, anhyddysg
Il-le-gal, anghyfreithlawn
Il-lic-it, anghyfreithlawn, annheg
Ill-na-ture, drwg dymher