Er in Fausset's Bible Dictionary

("watchful".) 1. Firstborn of Judah, by Bathshua, a Canaanite; the marriage with this daughter of a corrupt race producing sin and sorrow. Tamar was his wife but bore him no son; for "Er was wicked in the sight of the Lord, and the Lord slew him," his sin being probably some abomination connected with the impure Canaanite idolatry (Genesis 38:3-7). Genesis 38:2. 1 Chronicles 4:21. 3. Genesis 46:16. 4. Luke 3:28.