Originally Posted by Conor
A quick search in the web and Wikipedia reveals,
"The name "hamster" is a loanword from the German, which itself derives from earlier Old High German hamustro. It is possibly related to Old Russian choměstrǔ, which is either a blend of the root of Russian khomiak "hamster" and a Baltic word (cf. Lithuanian staras "hamster") or of Persian origin (cf. Av hamaēstar "oppressor")."
More info http://en.m.wikipedia.org/wiki/Hamster
Don't think that's quite the answer the op was looking for
now I could be wrong but i think it's called a "hamster" because it sounded better than calling it a "Gerbil"
and "Mouse" would have confused things even more
Ok! I will get my coat