Frank-hearted is a term used to describe someone who is open, honest, and straightforward in their manner of speaking. Some synonyms for this term include blunt, candid, forthright, sincere, and genuine. These words all indicate someone who is not afraid to speak their mind and be transparent with others. Other synonyms for frank-hearted may include open-minded, earnest, frank, and plainspoken. These terms all suggest that the person in question is trustworthy, reliable, and genuine in their communication style. Whether you are describing yourself or someone else, these words can be useful in communicating important traits and characteristics to others.