noun

a feature that renders something less acceptable; a disadvantage or problem.

the main drawback of fitting catalytic converters is the cost

disadvantage,snag,downside,stumbling block,catch,hitch,pitfall,fly in the ointment,weak spot/point,weakness,flaw,defect,imperfection,fault,handicap,limitation,trouble,difficulty,problem,issue,complication,liability,nuisance,hindrance,obstacle,hurdle,impediment,obstruction,inconvenience,barrier,curb,check,discouragement,deterrent,damper,disbenefit,minus,hiccup,spanner in the works,monkey wrench in the works