"Am extant" refers to something that exists at present or continues to exist. The antonyms for "am extant" would be words that describe something that does not exist or has ceased to exist. These antonyms can include phrases like "nonexistent," "extinct," "vanished," "forgotten," or "disappeared." These words can describe things that were once present but are no longer around, such as extinct species or forgotten cultures. It is important to remember that antonyms can have varying degrees of intensity and meaning, so choosing the right antonym for a particular context requires careful consideration of the intended meaning.