literally "(land of the) Middle Saxons" (those between Essex and Wessex); originally a much larger region. See middle (adj.) + Saxon.
Entries linking to middlesex
Essex
Old English East-Seaxe "East Saxons," who had a 7c. kingdom there. See east, Saxon.
Wessex
Anglo-Saxon kingdom in southern England, literally "(land of the) West Saxons;" see west + Saxon. Modern use in reference to southwestern England (excluding Cornwall) is from Hardy's novels.