mid-
/mɪd/combining form
1- denoting the middle of表示“…的中间（或中部、当中）”：
midsection.
1.1
- in the middle; medium; half表示“中间的”, “中部的”, “半的”：
midway.
词源
Old English midd, of Germanic origin; from an Indo-European root shared by Latin medius and Greek mesos.