We don't have synonyms for ne'er-do-well yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are neer-do-well, ne'er do well and ne'er-do-wells.
°A person without a means of support; an idle, worthless person; a loafer; a person who is ineffectual, unsuccessful, or completely lacking in merit; a good-for-nothing.
°A person without a means of support; an idle, worthless person; a loafer; a person who is ineffectual, unsuccessful, or completely lacking in merit; a good-for-nothing.