Atad

"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."

Definition of Atad:
"a thorn"