四日

1. Origins, structure, and basic meaning

• Structure: Spelling: 四日. Reading: よっか. Core meaning: four days; fourth day.
• Basic usage: Representative examples: 旅行から帰って四日が過ぎた / 会議は来月の四日に開かれる予定だ.

2. Common pitfalls and similar expressions

• Duration and calendar date
  • In 四日が過ぎた, the word means a duration of four days; in 来月の四日, it means the fourth day of the month. Both senses are read よっか.