hair shirt

A self-imposed punishment or penance. The term comes from the medieval practice of doing penance by wearing a shirt made of coarse haircloth (made from horsehair and wool), mentioned from the thirteenth century on in numerous sources, including Chaucer’s Canterbury Tales (The Second Nun’s Tale). It also appears in a couplet by Alexander Pope (1737), “No prelate’s lawns with hair-shirt lin’d is half so incoherent as my mind.” See also SACKCLOTH AND ASHES.