Longman Dictionary of Contemporary English - counter-

~ prefix 1 the opposite of something  (a counterproductive thing to do (=producing results opposite to what you wanted)) 2 matching something  (my counterpart in the American system (=someone who has the same job as mine)) 3 done or given as a reaction to something, especially to oppose it  (proposals and counter-proposals) 4 acting to prevent something  (a counterinsurgency strategy (=to prevent insurgents))