The antonyms for the word "un-fastidious" are numerous and diverse. Some examples of words that are opposite in meaning to this word include meticulous, precise, fussy, scrupulous, exacting, and demanding. These words are all associated with a high level of attention to detail, care, and precision, and are used to describe people who are painstakingly thorough and detail-oriented. In contrast, the word "un-fastidious" implies a lack of concern for or attention to detail, and is often used to describe careless, sloppy, or nonchalant individuals. To be precise, the antonyms of "un-fastidious" include those descriptive terms for those who are exacting, meticulous, and careful.