The phrase "be subsequent to" refers to something that comes after or follows another event or action. Its antonyms, therefore, would be words that express the opposite meaning such as "precede" or "prioritize". If something precedes another, it happens before it, whereas if something is prioritized it is given a higher importance in order of execution. Other antonyms for "be subsequent to" include "anticipate" which means to expect or look forward to something that has not yet happened or "delay" which means to postpone or make something happen later than planned. These antonyms provide a range of ways to contrast the idea of something following or happening after another event.