Most never failing is a phrase which describes something that is highly dependable and reliable. To find antonyms for this phrase, we must search for words that mean the opposite of never failing or words that indicate a lack of trustworthiness. Some suitable antonyms for most never failing can be doubtful, uncertain, unreliable, undependable, fallible, inconsistent, capricious or whimsical. These antonyms suggest that the attribute of never failing is absent or at least not completely trustworthy. As a result, these traits can lead to uncertainty or unreliability, leading to unfavorable outcomes in any activity where these factors are present.