vacillate

This term describes a state of indecision characterized by a rhythmic shifting from one position to another. When applied to human behavior, it suggests a lack of resolve or a psychological instability that prevents a final commitment. It carries a more formal and clinical tone than "hesitate," implying a repetitive cycle of changing one's mind rather than a simple pause before acting.

In a physical sense, the word evokes the image of a pendulum or a needle on a dial. This mechanical oscillation mirrors the mental instability of the first definition, linking the physical act of swaying with the intellectual act of wavering. It is typically used in technical or descriptive contexts to denote precise, repetitive movement.