Entry 1 sense Webster, 1913 fluctuating · fluc·tu·at·ing · IPA /flˈʌktʃəwˌeɪtɪŋ/ 01 adj. moving irregularly in an oscillatory manner, especially up and down; as, fluctuating prices. 1. moving irregularly in an oscillatory manner, especially up and down; as, fluctuating prices.