The term comes from the word "Landlord", and it refers to a person, who is the lord/boss/owner of one or several bitches. - A bitch here is not the formal term of the female dog, but a bitch person.
Other, less significant synonyms: Bitch owner, Bitch boss, and the Spanish version - Amo Puta - is also widely spread.

Mercury retrograde is the act of taking a shit whilst mooning one or more human beings. Your day can typically being going well, according to your horoscope, until you are forced into witnessing Mercury retrograde. Performing Mercury retrograde will often speed the astrological cycle forward for the individual performing the Mercury retrograde, bringing about happy and fruitful times to come.

the lord of bitches, the biggest bitch you have ever met, of all things bitchy

A senior from the LHS soccer team who owns a freshman, otherwise known as a bitch. Each bitchlord is able to claim one bitch of his own and haze the shit out of said bitch.