Pronunciation: (gran'fä"&thslash;ur, grand'-), [key]
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.
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.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.