Taken as a measure against something anticipated or feared; preventive. The company took preemptive action to avoid a hostile takeover.
Relating to the right to purchase something before others. The shareholders were given preemptive rights to buy additional shares before they were offered to the public.
Made or done in order to forestall or prevent an opponent’s move, especially a high-level opening bid in contract bridge. Her preemptive bid of three spades left the opponents with little room to respond.
Having the power to supersede, annul, or render ineffectual something else, especially of a law or regulation that overrides another. The statute's preemptive effect bars any conflicting state legislation.