sackcloth

Sacking.

A rough cloth of camel's hair, goat hair, hemp, cotton, or flax.

Garments made of this cloth, worn as a symbol of mourning or penitence.

Cloth of which sacks are made, usually a cloth of hemp or flax.

A coarse kind of cloth worn as a sign of grief, humiliation, or penitence; hence, the garb of mourning or penance.