what does "TMZ" stand for?

It stands for Thirty Mile Zone...

"The term “Thirty Mile Zone” originated in the 1960s, when due to the growth of location shoots, studios established a “thirty mile zone” to monitor rules for filming in Hollywood. The center of the zone was the offices of The Association of Motion Pictures and Television Producers, formerly at Beverly and La Cienega Boulevards in Los Angeles. TMZ reinvented the thirty mile zone and now serves as the Internet’s premiere address for entertainment news.

TMZ' stands for "Thirty Mile Zone," a term which originated in the 1960's. Due to the growth of 'on location' shoots, studios and various talent guilds established a "thirty mile zone", outside of which shooting is considered to be a location shoot, requiring per dimes and other travel and living expenses to be paid. The zone remains centered in Los Angeles around the old offices of The Association of Motion Pictures and Television Producers at Beverly and La Cienega Boulevards in California. It was often said that "Everything entertainment happens in the 'Thirty Mile Zone.'" So essentially, the "Thirty Mile Zone" represents the center of Hollywood.

I am sure you can find more answers on Google.

TMZ' stands for "Thirty Mile Zone," a term which originated in the 1960's. Due to the growth of 'on location' shoots, studios and various talent guilds established a "thirty mile zone", outside of which shooting is considered to be a location shoot, requiring per diems and other travel and living expenses to be paid. The zone remains centered in Los Angeles around the old offices of The Association of Motion Pictures and Television Producers at Beverly and La Cienega Boulevards in California. It was often said that "Everything entertainment happens in the 'Thirty Mile Zone.'" So essentially, the "Thirty Mile Zone" represents the center of Hollywood.[4]

-Bekah

I think it stands for "The Movie Zone".