pro·hib·i·tive / prəˈhibitiv; prō-/ • adj. 1. (of a price or charge) excessively high; difficult or impossible to pay: the costs involved were prohibitive prohibitive interest rates.2. (esp. of a law or rule) forbidding or restricting something: prohibitive legislation. ∎ (of a condition or situation) preventing someone from doing something: a wind over force 5 is prohibitive.DERIVATIVES: pro·hib·i·tive·ly adv.pro·hib·i·tive·ness n.