油断

1. Origins, structure, and basic meaning

• Structure: 油断, read ゆだん, is a conventional noun and verbal expression for a lapse in vigilance.
• Basic usage: Use it for letting necessary attention lapse through familiarity or complacency, as in 作業で油断する.

2. Common pitfalls and similar expressions

• Grammar and combinations
  • The fixed warning 油断してはいけない means danger remains and vigilance must not relax; do not interpret the word literally through oil.