This term "hopper mouse" just got used in a recent question, and it seems to be a term that only people that have experience with snakes know. So what is a "hopper" mouse? What are the other terms used, and their definitions?
There a four terms used for different sizes of mice fed to snakes. In order from smallest to largest they are:
Pinky Is a mouse that's so young it hasn't developed it's fur yet. The term refers to the color of the mouse's skin.
Because it's basically a newborn mouse, it's obviously going to be the smallest size mouse you can get.
Fuzzy Is a mouse that's just a little bit older than a Pinky Mouse. Just old enough that it starts to grow it's fur. Hence, it's fuzzy.
Hopper Is a young mouse that is at the stage in development where it begins to move around. Since they're still quite young and developing, they move around more by hopping.
It's also used to refer to young gerbils (at least in my area), since gerbils move around by hopping on their back legs
Adult Mouse No explanation needed really. It's an adult mouse. It's fully grown, so it's the biggest size of a mouse you can get.
Rats are used for larger snakes, but don't carry the same slang terminology as mice. At least in my experience they're simply referred to as "small", "medium", or "large", rats.
The number of terms used will vary from supplier to supplier, as could what each one means, so there will be no single authoritative answer to this question.
For example, one of the UK's popular suppliers of frozen food for reptiles, http://frozenreptile.co.uk/, lists the sizes of mice as
but another supplier may well use a different breakdown. Also, the cut-off from one "size" to another could vary, either by weight or by girth.