sackcloth

From Middle English sakcloth, sekcloth, sekclath, sekklath, equivalent to sack +‎ cloth.

sackcloth (countable and uncountable, plural sackcloths)

1. A coarse hessian style of cloth used to make sacks.
2. (usually with “and ashes”, also figurative) Garments worn as an act of penance.

   Synonyms: hairshirt, cilice

   After he realised the gravity of his crime he spent some time wearing sackcloth and ashes.

sackcloth (not comparable)

1. Made of sackcloth.
   • 1834, L[etitia] E[lizabeth] L[andon], Francesca Carrara. […], volume III, London: Richard Bentley, […], (successor to Henry Colburn), OCLC 630079698, page 144:

     Next you saw her alone, a kneeling penitent at the foot of the crucifix; her long fair hair is unbound, and the sackcloth robe is girded by a cord round her slender shape: her hands are clasped, and tears are flowing fast from the quenched radiance of those shadowy eyes;...

• wear sackcloth and ashes

• “sackcloth”, in The Oxford English Dictionary, 2nd edition, Oxford: Clarendon Press, 1989, →ISBN.