居眠り

1. Origins, structure, and basic meaning

• Structure: 居眠り(いねむり) means dozing while seated or in the course of another activity.
• Basic usage: It describes nodding off on a warm train or during a meeting.

2. Common pitfalls and similar expressions

• Actual dozing compared with 眠気
  • 眠気(ねむけ) is the feeling of sleepiness. 居眠り refers to actually dozing, so 居眠りをした means that someone nodded off.