isaosa = grandfather (noun) (some things Google found for "isaosa": a rare term: Isaosa S.A. de C.V. is a fertilizer company in Mexico; user names)
Word derivation for "grandfather" :
Basque = aitona, Finnish = isoisä
Miresua = isaosa
This change is because I changed the word for big (see previous post). My previous word for grandfather was isaoni. This word is nearly a compound of father (isai) + big (osa).