擦る

1. Origins, structure, and basic meaning

• Structure: 擦る (reading こする) is a godan transitive verb meaning to rub a surface against something with repeated movement and friction.
• Basic usage: It is used for rubbing cold hands together or repeatedly scrubbing a stain with a cloth.

2. Common pitfalls and similar expressions

• Marking the tool
  • In 布で擦る, で marks the tool used for rubbing, while the affected surface or stain takes を.
• More than touching
  • 擦る focuses on movement that produces friction, not a single moment of contact.