dangerous

1. Origins, structure, and basic meaning

• Structure: 危 conveys danger or precariousness; its on-reading is き.
• Basic usage: 危ない, read あぶない, is an adjective; 危険, read きけん, refers to danger.

2. Common pitfalls and similar expressions

• Connecting to a noun
  • In 危ない橋, the adjective directly modifies the noun; 危険な橋 requires な. Both mean a dangerous bridge.
• Different predicate forms
  • 危ない can itself state that something is dangerous. 危険 forms a statement with endings such as 危険だ or 危険です.