Lissajous figure, back-and-forth, battledore and shuttlecock, beat, chain, coaction, coming and going, commutation, complementary distribution, concurrence, consecution, cooperation, counterchange, cross fire, cyclicalness, ebb and flow, engagement, exchange, fluctuation, flux and reflux, give-and-take, interaction, interchange, intercommunication, intercourse, interlacing, intermeshing, intermittence, intermittency, intermutation, interplay, intertwining, interweaving, interworking, lex talionis, measure for measure, mesh, meshing, meter, mutual admiration, mutual support, mutual transfer, mutuality, order, oscillation, pendulation, pendulum motion, periodicalness, periodicity, permutation, piston motion, progression, pulsation, quid pro quo, reappearance, reciprocality, reciprocation, reciprocity, recurrence, regular wave motion, reoccurrence, repetition, retaliation, return, reversion, rhythm, rhythmic play, rotation, row, seasonality, seesaw, seesawing, sequel, sequence, series, shifting, shuffling, sine wave, something for something, succession, teeter-totter, teeter-tottering, teeter, teetering, tit for tat, to-and-fro, tottering, train, transposal, transposition, undulation, ups and downs, vacillation, variation, vicissitude, wavering, wigwag