"Am the mark" is not a word, but a phrase that refers to being accurately pinpointed or identified. Antonyms for this phrase could include "off the mark," "inaccurate," "miss the target," "unidentified," or "uncertain." Perhaps a more relevant antonym would be "anonymous," meaning the person or object is not specifically known or identified. Another antonym could be "hidden," indicating that the subject is intentionally concealed or difficult to pinpoint. Overall, antonyms for "am the mark" imply a lack of certainty or accuracy in identifying a subject or target.