intermittent

Synonyms: alternate arrested broken by bits and pieces checked cyclic cyclical discontinuing discontinuous epochal every other fitful here and there hit-or-miss infrequent interrupted isochronal isochronous iterant iterative metrical now and then occasional on and off periodic periodical punctuated recurrent recurring rhythmic rhythmical seasonal serial shifting spasmodic stop-and-go

Antonyms: constant continual continuing perpetual regular