John Gill Commentary Genesis 38:3

"And she conceived, and bare a son; and he called his name Er." — Genesis 38:3 (ASV)

And she conceived, and bore a son, and he called his name Er. Which signifies a "watchman"; but the reason of the name given by the Targum of Jonathan is, "because he should die without children;" as if it was the same with Ariri, "childless".