midterm
/ˈmɪdtɜːm/noun
1- the middle of a period of office, an academic term, or a pregnancy（任期, 怀孕）中期; （学期）期中：
Nixon resigned in midterm
尼克松在任期一半时辞职了
as modifier midterm elections中期选举。
1.1
- N. Amer. an exam in the middle of an academic term〈北美〉期中考试。