Which word best describes a state of being uncertain or unable to decide about a course of action?

The word that best describes a state of being uncertain or unable to decide about a course of action is "ambivalent." This term specifically refers to having mixed feelings or contradictory ideas about something or someone. When a person is ambivalent, they experience uncertainty or indecisiveness due to conflicting emotions or motivations.

For instance, someone might feel both excited and fearful about moving to a new city, demonstrating ambivalence about that decision. This state of mixed emotions is central to the definition of ambivalence, making it the most fitting choice in the context of the question regarding indecision or uncertainty.