The antonyms for the word "un steadfast" include reliable, trustworthy, dependable, steadfast, constant, and faithful. These words denote the opposite of "un steadfast," which means inconsistent or unreliable. A reliable person or thing is someone or something you can count on, and they are predictable in their behavior. Trustworthy individuals are honest, sincere, and dependable. Dependable people are those who fulfill their promises, and they are consistently there when needed. Steadfast people are resolute and enduring, and they never give up in the face of adversity. A constant person is unchanging, while a faithful person is dedicated, committed, and loyal.