Толковый словарь английского языка Oxford English Reference - see-saw

n., v., adj., & adv. --n. 1 a a device consisting of a long plank balanced on a central support for children to sit on at each end and move up and down by pushing the ground with their feet. b a game played on this. 2 an up-and-down or to-and-fro motion. 3 a contest in which the advantage repeatedly changes from one side to the other. --v.intr. 1 play on a see-saw. 2 move up and down as on a see-saw. 3 vacillate in policy, emotion, etc. --adj. & adv. with up-and-down or backward-and-forward motion (see-saw motion). Phrases and idioms go see-saw vacillate or alternate. Etymology: redupl. of SAW(1)