pendulate
/ˈpɛndjʊleɪt/ /ˈpɛndʒʊleɪt/verb
1 [no object] To dangle, sway to and fro; to oscillate.
2 [no object] Figurative. To fluctuate or oscillate between two opposite conditions, opinions, etc.; to waver, vacillate.
Origin
Late 17th century; earliest use found in Christ Exalted. Partly from pendulum + -ate, and partly from pendule + -ate.