prohibitive /pɹəˈhɪbɪtɪv/adjective 4noun 1forms 3 adjective4 •Tending to prohibit, preclude, or disallow.Some countries are more prohibitive than others when it comes to hot topics like euthanasia and cloning. •Requiring an unreasonable or impractical effort. •Costly to the extreme; beyond budget.I'd like to visit Europe someday, but the cost is prohibitive right now. •(US) Being the presumptive or likely winner of a contest.“I think there’s no question about that. I think he’s the prohibitive favorite if he gets in,” Dennis Lennox, a Michigan-based Republican political consultant, told Politico. — 2017 noun1 •A negative imperative. formsprohibitives · more prohibitive · most prohibitive