seesaw

Etymology

Probably a frequentative imitative of rhythmic back-and-forth, up-and-down or zigzagging motion, such as teeter-totter, zigzag, flip-flop, ping pong, etc., under the umbrella term of reduplication; also likely influenced by the verbs see and saw of either present or past tense.

noun

1. A structure composed of a plank, balanced in the middle, used as a game in which one person goes up as the other goes down.
2. A series of up-and-down movements.
3. A series of alternating movements or feelings.
   Manchester Citykept up their unbeaten start to the Premier League season with victory over QPR in an entertaining see-saw encounter at Loftus Road. November 5, 2011, Phil Dawkes, “QPR 2 - 3 Man City”, in BBC Sport
4. (medicine, attributively) An abnormal breathing pattern caused by airway obstruction, characterized by paradoxical chest and abdominal movement.

verb

1. (intransitive) To use a seesaw.
2. (intransitive, by extension) To fluctuate.
   When I think of your kisses / My mind see-saws 1971, “All I Want”, in Blue, performed by Joni Mitchell
3. (transitive) To cause to move backward and forward in seesaw fashion.
   He see-saws himself to and fro. 1832, Edward Bulwer-Lytton, Eugene Aram

adj

1. fluctuating.