Easton's Bible Dictionary

Forehead - The practice common among Oriental nations of colouring the forehead or impressing on it some distinctive mark as a sign of devotion to some deity is alluded to in Rev. 13:16, 17; 14:9; 17:5; 20:4.

The "jewel on thy forehead" mentioned in Ezek. 16:12 (R.V., "a ring upon thy nose") was in all probability the "nose-ring" (Isa. 3:21).

In Ezek. 3:7 the word "impudent" is rightly rendered in the Revised Version "an hard forehead." (See also ver. 8, 9.)