暖まる

1. Origins, structure, and basic meaning

• Structure: 暖まる, read あたたまる, is an intransitive verb meaning to warm up or become warm.
• Basic usage: 手足が暖まった reports warmed limbs; 部屋が暖まるまで sets the room's warming as an endpoint for waiting.

2. Common pitfalls and similar expressions

• Changing subject and temporal endpoint
  • What becomes warm takes が. 暖まった is completed, whereas 暖まるまで points to a future threshold.