無理

1. Origins, structure, and basic meaning

• Structure: 無理 (むり) is a noun and na-adjective for impossibility or effort that exceeds a person's condition or capacity.
• Basic usage: 無理だ judges something impossible, while 無理をする means to overexert or push oneself too far.
  • 重い荷物を一人で運ぶのは無理です。 — It is impossible to move the heavy load alone.
  • 疲れているときは無理をせず、早めに休みます。 — When I am tired, I do not push myself and rest early.

2. Common pitfalls and similar expressions

• Impossibility and overexertion
  • 無理です says that a task is not feasible, whereas 無理をしない means not placing excessive strain on oneself. Context distinguishes the two uses.