oscillate

Etymology

From Latin ōscillātus, perfect passive participle of Latin ōscillō (“swing”), from ōscillum (“a swing”), usually identified with ōscillum (“a little face or mask hung on a tree that sways with the wind”), diminutive of ōs (“mouth, face”).

verb

1. (intransitive) To swing back and forth, especially if with a regular rhythm.
   A pendulum oscillates slower as it gets longer.
2. (intransitive) To vacillate between conflicting opinions, etc.
   The mood for change oscillated from day to day.
3. (intransitive) To vary above and below a mean value.