the Fatwa Department Research Committee - chaired by Sheikh `Abd al-Wahhâb al-Turayrî
The meaning of the English word "lord" is not exclusively for Allah.
It is linguistically used for a person who is in authority over an estate or over a jurisdiction. It is used metaphorically for God (just like the word "king" is used).
Even in Arabic, the word which is translated as Lord – rabb – has other uses. It can be used in various phrases to mean different things. Rabb al-manzil (head of the house), rabbah al-bait (mistress of the house), rabb al-mâl (capital investor) arbâb al-funûn (artisans) are some examples.
In Arabic, however, the word rabb is never used on its own except as an epithet of Allah. It is only used for people when it is qualified by other words, as in the examples above.
This is not the case in English with the word "lord". Its spectrum of meanings is broader, and a Muslim speaking English can use it in accordance with English conventions. Its meaning is defined by its context. In some contexts, it only applies to the Divine. In other contexts, it applies to various civil authorities. When used as such – like saying 'My Lord' when addressing a judge at a court of law – there is no problem, since there is no ambiguity or misunderstanding regarding the intent.
Please know that there is rarely 100% correspondence of meaning between specific words in two different languages. Each language's words must be used properly according to the conventions of the language in question.
And Allah knows best.
Source: Islam Today