teeter-totter
noun (North American English)(also see-saw British and North American English)
a piece of equipment for children to play on consisting of a long flat piece of wood that is supported in the middle. A child sits at each end and makes the teeter-totter move up and down. 跷跷板：一种供儿童玩耍的设备，包括一块中间支撑的长木条。一个孩子坐在两端，使跷跷板上下移动。 Word Originlate 19th cent.: reduplication of teeter or totter.