An annoying freshman who thinks they're the shit and tries to hang out with all upperclassmen, usually sophomores. They stick their noses up at their fellow freshmen and act as if they are superior (this tends to make them hated by their class). They don't seem to realize that they'll be screwed senior year...
A 10th grade person (sophomore) is taking one or more 9th grade (freshman) classes because they didn't get enough credits in that class for that particular semester. it is an obvious combination of the words FRESHman and sophoMORE, and just replacing E with O. See? FROSHMORE.
Person A: aw man I failed the first semester of math and world geography, but I still got enough credits to make it to sophomore year!
Person B: yeah but that means you have to take the main topic of those semesters if you want to pass them. and you know what that means...
Person A: NOOO!!! I'm a froshmore!!!!
Rad dude A: .......... Dude, chill out. it's just a name it doesn't even mean anything except you're taking a few freshman level classes for like half of the year.