There are multiple origins and translations for the name Er:
1. Turkic (Turkish, Kazakh ер) name-giving and translates as - "man; brave; hero; soldier". Comes from Chinese (兒) [Ar] which actually means - "son".
2. Hebrew (עֵר) name semantics - "awake, alert, wakeful". Er - was the eldest son of Judah, and is described as marrying Tamar. According to the text, God killed Er because he was wicked, although it doesn't give any further details. In Hebrew Er spelled backwards spells 'evil.' According to Rashi and other rabbis, he, like Onan, purposely tried to keep Tamar from conceiving, in his case because he was afraid of spoiling her beauty. In the text, Er is portrayed as the brother of Onan and Shelah. The Book of Chronicles lists an Er as being one of Shelah's sons.
3. Germanic name-forming and interpretation is - "he".
4. Bashkir (ер) name-forming and definition is - "land; Earth".