Sack is a pure Hebrew word, and has spread into many modern languages. Sackcloth is a very coarse stuff, often of hair, Revelation 6:12. In great calamities, in penitence, in trouble, the Jews, etc., wore sackcloth about their bodies, Genesis 37:34; 2 Samuel 3:31; 1 Kings 20:32; Matthew 11:21. The prophets were often clothed in sackcloth, and generally in coarse clothing, Matthew 11:21. The Lord bid Isaiah put off the sackcloth from about his body, and go naked, Isaiah 20:2. Zechariah says, Zechariah 13:4, that false prophets should no longer prophesy in sackcloth, (English translation, a rough garment,) to deceive the simple.

In time of joy, or on hearing good news, those who were clad in sackcloth cast it from them, and resumed their usual clothing, Psalms 30:11.