The phrase "wast on one tail" means to be unsuccessful or wasted effort. There are several synonyms that can be used in place of this phrase, such as fruitless, pointless, unproductive, futile, ineffective, and in vain. These words convey the idea of not achieving a desired outcome or result. Additionally, synonyms like idle and empty show the sense of a lack of purpose in actions or endeavors. Conversely, successful synonyms such as prosperous, fruitful, and lucrative denote a positive outcome. Therefore, the selection of appropriate synonyms depends on the context and desired connotation of the statement.