How to adjust a pattern

[cookworm]

I really want to make this dress (it's from "Crochet Me!"), but the largest bust size they go up to is a 40" bust; I need it to fit a 44" bust. The pattern states it has something called a "negative ease"--what is that? (I probably should know this term but I don't). With regards to the negative ease, the pattern states if you want it to be a bit larger, go for the next largest size. So should I be aiming for something maybe even geared for a 46" size?