The antonyms for the word "be subsequent" are as follows; prior, preceding, former, previous, antecedent, foregone, earlier, antediluvian, preexisting, antiquated, outdated, bygone, and past. All these words are used to show that something existed or occurred before another event or thing. The opposite of subsequent is the preceding, which means happening or existing before someone or something else. It's important to understand the antonyms of words to achieve better communication skills and to be more precise in writing and speaking. Learning antonyms also helps expand one's vocabulary and improve overall language skills.