歳月

1. Origins, structure, and basic meaning

• Structure: 歳月 is read as さいげつ and is a noun for a long span or the passage of years.
• Basic usage: Taking many years appears in 長い歳月をかける, while ten years passing appears in 十年の歳月が流れる.

2. Common pitfalls and similar expressions

• Required span and passage of time
  • Use をかける for a required span and が流れる for time passing.
• Difference from 時間
  • 歳月 readily evokes many years rather than time spans in general.