Similar word to showstopper:

adjournment, bind, check, cooling-off period, cunctation, dawdling, demurral, detention, discontinuation, downtime, filibuster, hangup, hindrance, hold-up, holding, holding pattern, impediment, interval, jam, lag, lingering, logjam, loitering, moratorium, obstruction, postponement, problem, procrastination, prorogation, putting off, remission, reprieve, retardation, retardment, setback, showstopper, stall, stay, stop, stoppage, surcease, suspension, tarrying, tie-up, wait