"Backed and fill" is an idiomatic phrase that refers to the act of indecisiveness or inconsistency. It's often used to describe situations where someone changes their mind or direction repeatedly. There are several synonyms for this phrase, such as vacillate, waver, hesitate, oscillate, fluctuate, and dither. Vacillate means to be indecisive, waver means to be uncertain, hesitate means to pause or delay, oscillate means to swing back and forth, fluctuate means to vary, and dither means to be undecided. These synonyms perfectly capture the essence of the phrase "backed and fill" and can be used interchangeably depending on the context and tone of the situation.