Keddie is a Scottish surname, originally a nickname for surname MacAdam 'son of Adam', Adam being from the Hebrew adama 'earth'. Keddy, Kedie, Kiddie and Kiddy all occur also. In Gaelic Adam is rendered Adhamh and the ususal nn is Adie. This led to surnames McAddie, McAdie, McCaddie, McCadie, etc. - lop off the Mc from McCadie and what you'll hear is Keddie so it too became established as a surname and in UK tradition, family surnames are often used as the 2nd or 3rd given name.