赤旗

1. Origins, structure, and basic meaning

• Structure: 赤旗, read あかはた, is a compound noun directly joining the color 赤 with flag 旗.
• Basic usage: It denotes a red flag itself or a signal of danger or suspension, as in 赤旗を上げる.

2. Common pitfalls and similar expressions

• Scope and context
  • Unlike descriptive 赤い旗, 赤旗 can name an established signal or marker.