We don't have synonyms for nebish yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are nebbish, newish and neish.
(n) :
Alternative form of nebbish. [One who is fearful, indecisive and timid, especially in making decisions and plans, in discussions, debates, arguments, and confrontations, and in taking responsibility.]
(n) :
Alternative form of nebbish. [One who is fearful, indecisive and timid, especially in making decisions and plans, in discussions, debates, arguments, and confrontations, and in taking responsibility.]