The word "goof-up" is colloquially used to refer to a mistake or an error. Antonyms for this word may include precise, accurate, correct, faultless, or flawless. These words denote a sense of efficiency and correctness in actions or outcomes, which is the opposite of goofing up. Additionally, synonyms like well-executed, thorough, meticulous, or seamless can also be considered antonyms to goof-up. These words connote a sense of care and attention to detail, which is crucial to avoid mistakes. Using these antonyms instead of goof-up can help to express competency and capability in performing tasks, rather than the presence of errors.