Single-heartedness refers to a state of being completely devoted and sincere in one's intentions, actions, and feelings. Synonyms for this word include sincere, genuine, honest, upright, and principled. Other words that can be used to describe this quality include wholehearted, steadfast, committed, loyal, dedicated, and faithful. These words all denote the idea of being focused, undivided, and driven in pursuing a specific goal or objective. They also suggest a sense of integrity, righteousness, and moral uprightness, signaling the highest form of commitment and dedication to a specific cause, idea, or belief system. Overall, synonyms for single-heartedness all describe an unwavering commitment and steadfastness in pursuing a noble and virtuous path in life.