The antonyms for the word "half-done" are many, depending on the context. One opposite could be "fully done," which means that the task has been completed thoroughly and to a satisfactory level. Another antonym that comes to mind is "complete," which means that the job has been finished in its entirety. Other possible antonyms for "half-done" could be "perfect," "meticulous," "accurate," or "flawless," each implying that the job has been done to an exemplary standard. Ultimately, the antonyms for "half-done" all suggest that the job has been completed well, and without any gaps or weaknesses left unaddressed.