厄日

1. Origins, structure, and basic meaning

• Structure: 厄日 (やくび) is an unlucky or exceptionally bad day.
• Basic usage: 今日は厄日だ judges the current day; その日は厄日だった looks back on a day of several failures.

2. Common pitfalls and similar expressions

• Present and past judgment
  • The noun evaluates the whole day marked by accumulated misfortune, with だ for the present and だった for the past.