留守

1. Origins, structure, and basic meaning

• Structure: 留守, read るす, means being absent from home or another place where one would normally be.
• Basic usage: In 配達員が来たときは留守だったので、不在票が入っていた。, no one is home when the delivery driver arrives, so a missed-delivery notice is left.

2. Common pitfalls and similar expressions

• Absence over a period or at a moment
  • 留守にしている describes remaining away, while 留守だった reports absence at the time of a visit. The neighbors' schedule and the delivery driver's arrival frame that absence over different spans of time.