hair shirt
US /ˈher ˌʃɜrt/
UK /ˈher ˌʃɜrt/

1.
cilice
a shirt made of coarse animal hair, worn next to the skin as a penance or mortification of the flesh
:
•
In medieval times, some ascetics wore a hair shirt to demonstrate their devotion.
Au Moyen Âge, certains ascètes portaient un cilice pour montrer leur dévotion.
•
The monk's severe penance included wearing a rough hair shirt.
La pénitence sévère du moine incluait le port d'un rude cilice.
2.
fardeau, source de tourment
something that causes constant discomfort or annoyance, especially as a self-imposed burden
:
•
His constant worrying about trivial matters was a real hair shirt for him.
Ses inquiétudes constantes pour des bagatelles étaient un véritable cilice pour lui.
•
Living with such strict self-imposed rules became a kind of hair shirt.
Vivre avec des règles auto-imposées si strictes est devenu une sorte de cilice.