Pronunciation: (gran'fä"&thslash;ur, grand'-),[key] —n. 1. the father of one's father or mother.
2. a forefather.
3. the founder or originator of a family, species, type, etc.; the first of one's or its kind, or the one being longest in existence: the grandfather of all steam locomotives.
—v.t. to exempt (something or someone) from new legislation, restrictions, or requirements: The law grandfathered all banks already operating at the time of passage. He was grandfathered into the pension plan.