pro·lif·i·ca·cy \-fə̇kəsē, -fēk-, -si\noun (-es) Etymology:prolific + -acy (as in efficacy) : the quality or state of being prolific < the emergence of paperback books in a prolificacy unknown on these shores — Times Literary Supplement > especially: the quality or state of producing young in large numbers or at frequent intervals < the prolificacy of rabbits >