There is no such thing as a “neb” “nebbish” or “nebach” by Torah Definitions. This is ambivalent colloquialism that has sadly permeated out Jewish communities and is quite discriminatory.
Torah defines the underserved portion of our communities as indigent, poor, wicked, foolish, disgruntled, ambivalent, unorthodox, wretched, petty, childless (and that is not a derogatory thought), pain stricken, evil, narcissistic, discheveled, unworthy, sick, ridiculed, spent, tasteless and likely many other ways. Calling someone a nebbish makes you the “nebbish” in my eyes. I will never use that disgusting and dirty way of describing a human being who has some worth.
Sad that our communities that are so cohesive have such an ugly way of talking when we have Torah to guide us instead.