If you're looking for the past participle of a related verb, there are two possibilities:
* "Subject" as a verb: This is a less common usage, meaning "to bring under control" or "to expose to something." Its past participle is "subjected."
* "Subdue" as a verb: This means "to bring under control" or "to overcome." Its past participle is "subdued."
Let me know if you have another word in mind!