Which term would best describe someone characterized by forthrightness or uncompromising behavior?

The term that best describes someone characterized by forthrightness or uncompromising behavior is obstinate. Being obstinate refers to a person's tendency to be stubborn and resistant to change or persuasion, often standing firm in their beliefs or opinions regardless of opposing views. This aligns well with the idea of being forthright, as such individuals express their thoughts and positions candidly without yielding easily to counterarguments or pressure.

The other terms have different connotations that do not align with the behavior described. Agreeable suggests a willingness to please others and accommodate differing opinions, which contrasts with being uncompromising. Balky implies a tendency to resist or be difficult, but it often implies a reluctance to engage rather than a straightforward stance. Submissive denotes a readiness to yield to others, which is the opposite of forthrightness and uncompromising behavior.