1. (n.) One who hinders progress; one who obstructs business, as in a legislative body.

2. (a.) of or pertaining to obstructionists.

bitter-ender brawler defendant diehard disputant dissentient dissident filibuster filibusterer frustrater hinderer impeder intransigent irreconcilable last-ditcher litigant marplot naysayer negativist noncooperator objector obstructer obstructive opposer oppositionist plaintiff protester quarreler resister scrapper thwarter wrangler