father has 19 distinct synonyms spread across 8 of its 9 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is mother.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a male parent (also used as a term of address to your father)
“his father was born in Atlanta”
(Christianity) any of about 70 theologians in the period from the 2nd to the 7th century whose writing established and confirmed official church doctrine; in the Roman Catholic Church some were later declared saints and became Doctor of the Church; the best known Latin Church Fathers are Ambrose, Augustine, Gregory the Great, and Jerome; those who wrote in Greek include Athanasius, Basil, Gregory Nazianzen, and John Chrysostom
a person who holds an important or distinguished position in some organization
“the tennis fathers ruled in her favor”
God when considered as the first person in the Trinity
“hear our prayers, Heavenly Father”
a person who founds or establishes some institution
“George Washington is the father of his country”
Synonyms, antonyms and the broader and narrower relations for father come from Princeton University’s WordNet. Full sources and licences.