"Hath do" is an archaic phrase used in the English language that means "to have done." There are many synonyms for "hath do" that can be used in modern speech or writing. Some examples are "completed," "finished," "accomplished," "achieved," "concluded," "carried out," and "executed." Each of these words suggests the idea of having completed a task or activity. If you want to use a more modern phrase to substitute "hath do," some examples are "job done," "mission accomplished," "finished task," or "task achieved." Overall, using a synonym for "hath do" will help you communicate effectively and make your writing or speech sound more natural and up to date.