proliferation proliferation /ˌproʊlɪfɝˈeɪʃən/

noun

1. () Growth by the rapid multiplication of parts  ( proliferation )
   growth by the rapid multiplication of parts
     The rapid proliferation of cells contributed to the tumor's growth.
   The rapid proliferation of cells contributed to the tumor's growth.
   
2. A rapid increase in number (especially a rapid increase in the number of deadly weapons)  ( proliferation )
   a rapid increase in number (especially a rapid increase in the number of deadly weapons)
    The proliferation of nuclear weapons
   the proliferation of nuclear weapons