腕枕

1. Origins, structure, and basic meaning

• Structure: 腕枕 is read as うでまくら and is a noun for using an arm as a pillow for oneself or another person.
• Basic usage: Providing it to a child appears in 子どもに腕枕をする, while remaining in the pose appears in 腕枕のまま眠る.

2. Common pitfalls and similar expressions

• An arm used as a pillow
  • It denotes an action or position in which an arm supports a head, not a separate pillow object.
• Action and resulting position
  • 腕枕をする is the act of making an arm pillow, while 腕枕のまま means the position continues.