Explanation
Expresses the idea of 'unfitting', 'unbecoming' or 'inappropriate'.
Formation
Noun1 にあるまじき Noun2
Detailed explanation
The grammar point Noun にあるまじき Noun is used to express that the noun doesn't fit or is inappropriate in some way for the other noun. It can translate loosely as 'unfitting for', 'unbecoming of' or 'something that must not be for a/ the noun'.
Examples
彼は教師にあるまじき言動をとった。
Kare wa kyoushi ni aru majiki gendou wo totta.
He took actions that are unbecoming of a teacher.
これは人間にあるまじき行為だ。
Kore wa ningen ni aru majiki koui da.
This is an act that is unfitting for a human.
彼女は社長にあるまじき振る舞いをした。
Kanojo wa shachou ni aru majiki furumai wo shita.
She behaved in a way that is unbecoming of a president.
それは社会人にあるまじき行動だ。
Sore wa shakaijin ni aru majiki koudou da.
That is a behaviour that is not suitable for an adult.
Practice
Grammar content sourced from hanabira.org.