x1 is a nerd/geek (demonstrates esoteric intense interests at the cost of social acceptance) according to standard/within culture x2 with nerdy/geeky interests x3
Modeled on the definition of mugle. Some degree of (at least budding) expertise might be implied, but it is not truly necessary. There just has to be a degree of social rejection or isolation and an intense interest about (a) narrow and somewhat obscure subject matter(s). A nerd need not always be socially disconnected, but it should happen at least where x3 is involved or the interest becomes relevant/apparent. On the other hand, nerdiness/geekiness is also a personality (or a trait thereof), some sense, it never does not apply if it ever applies; but there are contexts wherein certain traits do not really emerge/reveal themselves readily. The intensity of interest in x3 should be judged to be excessive and abnornal, to the point of social separation, by/relative to x2.