The prefix mid-, which means “middle,” combines primarily with nouns to form compounds, most of which represent a time (midmorning, midsummer, midyear) or place (midbrain, midstream, midtown). When mid- is affixed to a word beginning with a capital letter, it is always necessary to use a hyphen: mid-November, mid-Atlantic states. The prefix mid- can be traced back to the Old English adjective midd, meaning “middle.