Composed of 非 (non-, un-) + 公式 (official, formal). The prefix 非 negates the base word. Functions both as a na-adjective (非公式な) and as a noun.
Common collocations
- 非公式な会談 (informal meeting/talks)
- 非公式な発表 (unofficial announcement)
- 非公式な訪問 (unofficial visit)
- 非公式に (informally, off the record)
Similar words
- 公式 — official, formal (the antonym)
- 私的 — private, personal (focuses on private vs. public rather than official status)
- オフレコ — off the record (journalism term, loanword from English)