From The Art and Popular Culture Encyclopedia
The Patriarchs (האבות HaAvot in Hebrew) of the bible are ancestors: in the narrowest definition they are Abraham, the ancestor of all the Abrahamic nations, his son Isaac, the ancestor of the nations surrounding Israel/Judah, and Isaac's son Jacob, also named Israel, the ancestor of the Israelites: these three figures are referred to collectively as the patriarchs of Judaism, and the period in which they lived is known as the Patriarchal period. Their primary wives – Sarah (wife of Abraham), Rebekah (wife of Isaac), and Leah and Rachel (the wives of Jacob) – are known as the Matriarchs. Thus, Judaism has three patriarchs and four matriarchs.
More widely the term can be used to refer to the twenty ancestor-figures between Abraham and Adam, the first man - the first ten of these, between Adam and Noah, are called the Antediluvian patriarchs, because they came before the Flood.