According to Wikipedia, "The Luddites were a social movement of British textile artisans in the early nineteenth century who protested – often by destroying mechanized looms – against the changes produced by the Industrial Revolution, which they felt threatened their livelihood."
Or, in more colloquial usage, someone who fears technology. For example, my boss, my step-mom, one of my history teachers in high school, and Stephen King (hence the photo). I prescribe a pretty broad definition to the term and use it to describe people who not necessarily fear technology, but are just plan bad it at. For example, I have to give my boss regular cut-and-paste tutorials. Granted, he grew up a different generation and kids today come out of the womb with an iPod in one hand, knowing what ROTFLMAO means (and I had to say out the words to type the acronym, mind you), but still, he's what I would call a Luddite.
Luddites are great. I don't know about the early nineteenth century Luddites, but I love Luddites today--they are such a rarity and I find them so entertaining. Like, why fear technology? Or why is it so hard to understand? Just embrace the fact that in ten years half the population will be robots. Or not. Whatever. Learn how to cut and paste though, please.