A dreadnought guitar has wider hips compared to its shoulders, like this:
http://www.encyclopedie-enligne.com/Images/1/150px-guitare_folk.jpg
It tends to have a powerful lower end. It tends to be more expensive to get a well made dreadnought, because the lower end can be too boomy.
An alternative is the folk bodied guitar, which has more rounded shoulders and hips and is less broad: http://musicianscentre.com/images/P/126426423653139.png
These not only give a more powerful midrange to high notes but are also easier to fit your arm round if you are petite.
If the guitar has a CE in the name, that means it’s got a cutaway—that’s where the body dips near the fretboard to let you get finger higher up the neck.
I hope this is helpful!