The phrase "job half done" refers to an incomplete task or project. Some synonyms that could be used in its place include "unfinished," "incomplete," "partially done," "inadequate," "insufficient," or "lacking." These words convey a sense of something that has not been completed to its full potential or has not met the desired standard. To give the phrase a slightly more positive connotation, one could use the synonym "work in progress," which implies that the task is not yet complete but is being actively worked on. Whatever word is chosen, it is clear that a job half done is not good enough.