According to Wikipedia the definition of glitch goes as follows:
A glitch is a short-lived fault in a system. It is often used to describe a transient fault that corrects itself, and is therefore difficult to troubleshoot.
I would like to add, that not only is it hard to troubleshoot, it is hard to control as a form of creative expression. A Glitch is a digital coincidence that in this particular case, created an interesting, yet short-lived result, which I luckily managed to export as a jpeg.