Lissajous figure, alternation, back-and-forth, coming and going, dilapidated, doddering, ebb and flow, fluctuation, flux and reflux, groggy, oscillation, pendulation, ramshackle, reciprocation, rhythmic play, ricketish, rickety, rocky, seesaw, seesawing, shaky, shifting, shuffling, sine wave, spidery, spindly, teeter-totter, teeter-tottering, teeter, teetery, to-and-fro, tottering, tottery, tumbledown, unsteady, ups and downs, vacillation, variation, vicissitude, wavering, wigwag, wobbly