mid (prep., adj.) Look up mid at Dictionary.com
Old English mid "with, in conjunction with, in company with, together with, among," from Proto-Germanic *medjaz (source also of Old Norse miðr, Old Saxon middi, Old Frisian midde, Old High German mitti, Gothic midjis "mid, middle"), from PIE root *medhyo- "middle." Now surviving in English only as a prefix (mid-air, midstream, etc.); as a preposition it often is a shortened form of amid (compare midshipman).