According to Wiktionary:
1. (Internet often derogatory) The physical world, as opposed to the virtual world of the Internet.
According to Dictionary.com:
1. (slang) The real physical world, as contrasted with with the world of cyberspace.
According to Urban Dictionary:
1. noun. A term, originating from cyberpunk fiction and culture, referring to the real (that is, not virtual) world, the world of flesh and blood. Somewhat tongue-in-cheek. The opposite of cyberspace.
"Writers, who can go for three or four days at a time without talking to people in 'meatspace' are particularly attracted to this form of friendship." - Andrew Brown
2. Deriving from cyberpunk novels, meatspace is the world outside of the net -- that is to say, the real world, where you do things with your body rather than with your keyboard. William Gibson's novels (Neuromancer, Mona Lisa Overdrive, and Count Zero in particular) note the difference between the net of the console cowboys and the world of the meat outside.
"For many a true computer geek, moving through meatspace is a daunting prospect."
"SimStim was a meat toy, which is why Case had never been able to get into it."