See sporadic in Webster's New World Roget's A-Z Thesaurus II
adjective
Happening or appearing now and then:
fitful, intermittent, occasional, periodic, periodical. (Informal) on-again, off-again. See continueRarely occurring or appearing:
infrequent, occasional, rare, scarce, uncommon, unusual. Idiom: few and far between. See usual
Learn more about sporadic