unqualified person; incompetent person; square peg in a round hole
Formal term for someone who is not suited or lacks the necessary qualifications for a position or task. Often used in professional or evaluative contexts.
He was judged to be unqualified for that job.
You shouldn't put an incompetent person in an important post.
Compound of 不 (not), 適任 (suitable for a post), and 者 (person). The word is a straightforward Sino-Japanese formation.