The phrase you’re looking for is usually “fluctuating” or “going up and down.” If you mean a physical object, common examples are a yo-yo , elevator , swing , or seesaw.

Common words

  • Fluctuate : to change repeatedly, especially up and down.
  • Rise and fall : a simple way to describe movement or changes in level.
  • Ups and downs : often used for changes in life, prices, moods, or trends.

Examples

  • A yo-yo goes up and down.
  • An elevator moves up and down.
  • A swing or seesaw also moves up and down.

Best fit

If you want one general word, use fluctuating. If you want a casual phrase, say it goes up and down.