every so often

adjective as in periodic

adverb as in at times

adverb as in ever and again

adverb as in every now and then

adverb as in intermittently

adverb as in now and then

adverb as in occasionally

adverb as in off and on

adverb as in on and off

adverb as in once in awhile

adverb as in once in a while

adverb as in sometimes