parliamentarian; member of a congress; Diet member
Specifically refers to a member of the Japanese National Diet (国会), though it can be used for members of other national legislatures in translation. In Japanese political context, it is a formal title for elected representatives.
He has long been active as a Diet member elected from his local district.
代議士会館には多くの議員事務所が入っている。
The Diet Members' Office Building houses many parliamentary offices.
He won the election and became a Diet member.
She plans to run for a Diet seat in the next election.
My grandfather served as a Diet member for many years.