Atad - (Easton's Bible Dictionary)
Buckthorn, a place where Joseph and his brethren, when on their way from Egypt to Hebron with the remains of their father Jacob, made for seven days a "great and very sore lamentation." On this account the Canaanites called it "Abel-mizraim" (Gen. 50:10, 11). It was probably near Hebron. The word is rendered "bramble" in Judg. 9:14, 15, and "thorns" in Ps. 58:9.