again and again Antonyms

could never happen once in a blue moon on and off off and on every so often every once in a while episodically at no time at intervals any more unsystematically every now and then certainly not can never happen by no chance only now and then on no occasion on rare occasions not often almost never hardly ever at the greek calends no longer no more never again rarely randomly periodically interruptedly infrequently inconsistently hardly desultorily chaotically scarcely seldom sporadically by fits and starts on occasion now and again from time to time at times at random by chance unoften temporarily accidentally