o'-nan ('onan, "vigorous"; compare ONAM, a "son" of Judah (Ge 38:4,8-10; 46:12; Nu 26:19; 1Ch 2:3); "The story of the untimely death of Er and Onan implies that two of the ancient clans of Judah early disappeared" (Curtis, Chron, 84). See Skinner, Gen, 452, where it is pointed out that in Ge 38:11 Judah plainly attributes the death of his sons in some way to Tamar herself. The name is allied to Onam.
The International Standard Bible Encyclopedia
Onan
The International Standard Bible Encyclopedia, James Orr (1915). Public domain, from the CrossWire SWORD module.