to grow or produce by multiplication of parts, as in budding or cell division, or by procreation.

to increase in number or spread rapidly and often excessively.

verb

decline , decrease , fall off

verb

breed , burgeon , engender , escalate , expand , generate , grow rapidly , multiply , mushroom * , procreate , propagate , reproduce , run riot * , snowball , increase , spawn , aggrandize , amplify , augment , boost , build , build up , enlarge , extend , grow , magnify , mount , rise , run up , soar , swell , upsurge , wax , mushroom , spread , sprout