全然

1. Origins, structure, and basic meaning

• Structure: 全然(ぜんぜん) is an adverb that strongly emphasizes a following state or judgment.
• Basic usage: With a negative expression, it means 'not at all.'
  • 全然分からなかった means that someone did not understand at all.

2. Common pitfalls and similar expressions

• With an affirmative expression
  • In conversation it can also accompany an affirmative expression, as in 全然平気です, meaning 'completely fine' or 'not bothered at all.'
• Compared with 全て
  • 全て(すべて) refers to all of something; 全然 emphasizes the following judgment or state.