Onan in the Bible Encyclopedia - ISBE

o'-nan ('onan, "vigorous"; compare ONAM, a "son" of Judah (Gen 38:4,8-10; 46:12; Nu 26:19; 1 Ch 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 Gen 38:11 Judah plainly attributes the death of his sons in some way to Tamar herself. The name is allied to Onam.