Undependable!

oscillate
(v)
OSS-i-late
Meaning

sway back and forth (like a pendulum)

1st Sample Sentence

1. Once set in motion, a pendulum will never cease to oscillate unless someone or something stops its movement.

2nd Meaning

2. sway back and forth (in a figurative sense); waver

2nd Sample Sentence

2. He is a very indecisive person, and tends to oscillate between to possible options until his wife tells him which one he should choose.

Root

oscillare (to swing) (Latin)

Mnemonics

Sounds like "Oh See Late", you get late because you are not able to decide which dress to wear, red or white. So you sway back and forth to decide.