noun, na-adjective, noun which may take the genitive case particle 'no'
defect; deficiency; incompleteness
Used for something that is lacking, incomplete, or not fully prepared, often in formal contexts such as documents, systems, or preparations.
提出書類に不備があったため、受け付けてもらえなかった。
The submitted documents had deficiencies, so they were not accepted.
計画にはまだ不備な点が
The plan still has many incomplete points.
expression
Archaic valediction used at the end of a letter, similar to 'Yours in haste' or 'Written in haste, forgive omissions'. Not used in modern correspondence.
古い手紙の末尾に「不備」とだけ書かれていることがある。
At the end of old letters, you sometimes see just '不備' written.