A synonym is a word that has a near identical meaning to that of another word. For example, happy and joyful are synonyms as they both mean nearly the same thing. An antonym is a word that has an opposite meaning of another word. As an example, hot is an antonym of cold.
The word archive means to file away. Other ways it can be defined are to collect or pull in. Archive has no direct antonyms. Antonyms only work when you are comparing two words and there is no single word that is the opposite of archive. The closest opposite meanings that are short are to mess up, fail to collect or push away. None of these count as antonyms.
Chronicle is a word similar to archive. It is a noun and means account. The word depository is another similar word. It's defined as a storage place. It can be used interchangeably with repository in most cases. Document is also similar and means written communication. Of these words, document is the only one with an antonym, which is speech.
Like antonym and synonym, archive is rooted in Latin. The origin of archive dates to 1595 and other meanings from the time include the equivalent to arch and public office. Archive can be used as a noun, since it can refer to a place ("It's in the archives"). It can also be used as a verb since it may mean that you are doing an action to something ("He was archiving those documents").