まじき (majiki): Unbecoming; must not
～まじき (majiki)
Meaning
Unbecoming; must not
Formation and usage
V dictionary + まじき + N
Notation: N = noun; V dictionary = dictionary-form verb; V stem = the stem before ます; plain clause = plain-form clause; negative stem = the form before ない. Follow the attachment shown above.
Explanation
Strongly condemns behavior as ethically unacceptable or unworthy of a role; formal and literary.
Examples
これは教師にあるまじき行為だ。
This is behavior unbecoming of a teacher.
これは医師にあるまじき行為だ。
This is behavior unbecoming of a doctor.
これは指導者にあるまじき行為だ。
This is behavior unbecoming of a leader.
これは経営者にあるまじき行為だ。
This is behavior unbecoming of a manager.
これは政治家にあるまじき行為だ。
This is behavior unbecoming of a politician.
How related patterns differ
たる invokes a role's qualities; たらんとする aspires to it. まじき and ともあろう者が condemn unworthy conduct. べからず prohibits, while てしかるべきだ states what is proper. These forms can be strong or old-fashioned, so register matters.