I. ˈgran(d)ˌ ̷ ̷ ̷ ̷, -raan- noun
Etymology: Middle English graund fader (translation of Middle French grant pere ), from Middle French grant grand + Middle English fader father — more at grand , father
1. : a father's or mother's father : an ancestor in the next degree above the father or mother in lineal ascent ; also : forefather
2. : one suggesting a grandfather in being a precursor in a line of similar things showing successive development, in being old and venerable, or in being the first or earliest in a line
the church supper is the grandfather of the country club — Saturday Review
an old grandfather of a tree
also : something sizable or impressive in a way suggesting a long period of growth or development
the grandfather of all buttons — Ben Riker
II. transitive verb
: to permit to continue under a grandfather clause
existing personnel would be grandfathered into the present system — Wall Street Journal
grandfathered water rights