Merriam-Webster Online Dictionary
grandfather (noun)1.
a) the father of one's father or mother
b) - ancestor
2.
- granddaddy
transitive verb
to permit to continue under a grandfather clause
Merriam-Webster Online Thesaurus
grandfather (noun)a person who is several generations earlier in an individual's line of descent
SYNONIMS:
father, forebear ( forbear), forebearer, forefather, grandfather, primogenitor, progenitorRELATED WORDS:
antecessor, predecessor []; ancestress, foremother, grandmother, matriarch; grandsire [], patriarch, sire []; ancestry, antecedents, rootsNEAR ANTONYMS:
children, family, issue, lineage, offspring, posterity, progeny, seed, stock; daughter, heir, inheritor, scion, son, successor