However, depending on the context, you could use prefixes like:
* Pre-: This emphasizes the idea of taking action before something happens. For example, "preemptive action" is similar in meaning to "proactive action".
* Anti-: This suggests taking action to prevent something negative from occurring. For example, "anticipate" and "anticipatory" can convey a similar meaning to "proactive".
* Fore-: This suggests anticipating something in advance. For example, "foresight" and "forewarned" can be associated with proactive thinking.
You could also use words like "preemptive," "preventative," "forward-looking," "strategic," " anticipatory," or "initiative-taking" to convey a similar meaning.
Ultimately, the best prefix or word to use depends on the specific nuance you want to convey.