One who is socially outcast either due to ineptness, idiosyncratic interests, or behavior. That's it. However, there are a few subcateogires.
1. One who does not realize they are doing anything wrong due to
ignorance about social conventions. This person
might want to be accepted but does not know how to become so. This variety is the most likely to suffer from bullying.
2. One who realizes they are not always accepted by peers because of varying reasons, such as an "
unpopular' interest or a refusal to accept social norms. In other words, they forsake acceptance for individuality. These are most likely to be a part of one the various
sub-cultures.
3. One who realizes they are not behaving in a socially acceptable manner but choose to go with it anyway because they think the "correct" manner is
stupid. Most likely to be a jerk.
Example 1:
"I wish I had more friends. I
just find social conventions to be
difficult to understand. Woe is me."
Example 2:
"I could be with the cool
kids, but at what cost? I'd rather be ostracized as a dork than have to give up my goth-y exterior. It's who I am."
Example 3:
...Nothing really is as good an example as Sheldon from The Big Bang Theory, is there? Just look him up.