fluctuate

Short definition from Wiktionary

Verb

1. 1
   To vary irregularly; to swing.
2. 2
   To undulate.
3. 3
   To be irresolute; to waver.
4. 4
   To cause to vary irregularly.
5. 5
   To rise and fall as a wave; to be tossed up and down the waves.

Adjective

1. 1
   Tossed up and down the waves.
2. 2
   Wavering, fickle.