Why are grandsons and other descendants sometimes called “sons” in the Bible?

In several instances, the Bible uses the word son in its broad, generic sense of “descendant.” So, in some contexts, a “son” could be what we might call a “grandson,” “great-grandson,” etc. The same principle holds true for the word father, which in some contexts can simply mean “ancestor” or “predecessor.”

A notable example of the word father referring to a grandfather is in Daniel 5. In that chapter, King Nebuchadnezzar is referenced several times as the “father” of Belshazzar:

Historically, we know that Belshazzar was the son of Nabonidus, the last king of the Neo-Babylonian Empire, but Scripture calls Nebuchadnezzar the “father” instead. The use of the word father here makes the point that Nebuchadnezzar, a more prominent king, was the royal predecessor—and possibly a grandfather—of Belshazzar. Belshazzar was the “son” of Nebuchadnezzar in the sense that he was a successor and perhaps a physical descendant.

An example of the use of son to refer to a more distant descendant is found in Genesis 29. Jacob was traveling east, and he arrived at a well and met some shepherds. He inquired of the shepherds about a relative of his: “Do you know Laban the son of Nahor?” (Genesis 29:5, ESV). The shepherds replied that they did indeed know Laban. Jacob’s reference to Laban as Nahor’s “son” is interesting, because Laban was actually Nahor’s grandson—a fact that Jacob would have known. Genesis 24 specifies that Laban was Rebekah’s brother (Genesis 24:29), and Rebekah was the daughter of Nahor’s son Bethuel (Genesis 24:24). But it was perfectly natural for Jacob to call Laban “the son of Nahor” because the word son could cover other descendants.

Later in the same story, Jacob and his family flee from Laban, and Laban pursues them. When he catches up to Jacob, Laban complains that “you not permit me to kiss my sons and my daughters farewell” (Genesis 31:28, ESV). The “sons” in this context are obviously Laban’s grandsons, born to his daughters, Leah and Rachel. Some translations, such as the NIV and NASB, clarify the relationship by translating the Hebrew word for “sons” as “grandchildren.”

A related topic is the practice of calling Jesus the “son of David” as in Matthew 9:27 and Matthew 20:30. The beginning of Jesus’ genealogy calls Jesus both the “son of David” and the “son of Abraham” (Matthew 1:1). Of course, many generations separated Jesus and David, and even more generations came between Jesus and Abraham. But being a “son,” in the thinking of the day, meant being a direct male descendant. No matter how many generations had passed, a son could still trace his lineage back to a well-known family representative.