Indie is short for independant (at least I think). But basically it means that you work on your own (or in a small team) using reletavley low cost software (as opposed to the £20K industry standard stuff) to produce small titles which you might sell from your website, or give away for free. Although there is nothing to say that and indie dev can't go on to create something bigger and get it published (one DarkBASIC user got 1st in the PC charts, although it wasn't a game
)
Hope that helps