灯る

1. Origins, structure, and basic meaning

• Structure: 灯る is read as ともる and can mean “to light up” or “to be lit”, depending on context.
• Basic usage: The examples show lights coming on along a bridge and a small light glowing in a window.

2. Common pitfalls and similar expressions

• Distinguishing senses and uses
  • It is intransitive for a lamp or light becoming lit; transitive 灯す means someone lights it.