Synonyms and related words :
alternately, back and forth, backward and forward, backwards and forwards, by turns, capriciously, changeably, desultorily, erratically, every other, hitch and hike, in and out, in rotation, in turns, inconstantly, make and break, mutatis mutandis, off and on, on and off, reciprocally, ride and tie, round and round, seesaw, shuttlewise, turn about, uncertainly, unsteadfastly, unsteadily, up and down, variably, vice versa, waveringly