- the father of one's father or mother.
- a forefather.
- 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.
- the father of one's father or mother
- a male ancestor
- a familiar term of address for an old man
- a caterpillar or woodlouse
