What is "my lord"

interj. (alternative form of oh my Lord English) n. 1 (context UK English) (non-gloss definition: Used in direct address to peers of the realm, usually now excluding dukes and the Lords Spiritual). 2 (context UK English) (non-gloss definition: Used in direct address to bishops, particularly Anglican ones.) 3 (context UK English) (non-gloss definition: Used in direct address to the Lord Mayors of certain important cities, including London and Canterbury.)