What term describes someone who is passive and unable to express opinions openly?

The term "unassertive" specifically refers to a person who tends to be passive and does not feel comfortable expressing their opinions or standing up for themselves in various situations. An unassertive individual might struggle with asserting their thoughts, needs, or feelings, often leading to a tendency to avoid conflict or confrontation.

This aligns perfectly with the definition of being unable to openly express opinions. In contrast, the other terms have different meanings or imply varying degrees of behavior. For instance, being reserved suggests a person who may be quiet or reflective but is not necessarily passive in terms of opinion expression; they may simply choose to speak less frequently. Passive-aggressive behavior involves indirect resistance and avoidance of direct confrontation, which does not accurately describe an inability to express opinions. Rebelliousness implies an active resistance to authority or norms, which is the opposite of being passive. Therefore, "unassertive" is the most suitable term for someone who is passive and unable to express their opinions openly.