The phrase "am offing" describes the act of leaving or departing from a place or situation. So, the antonyms for "am offing" would be words that express the opposite sentiment. Some antonyms for "am offing" could be "am arriving," "am staying," or "am remaining." Instead of leaving, one could be coming, arriving, or staying put. Other antonyms might include "am joining" or "am participating." These words suggest that the person is becoming more involved in the situation, rather than leaving or distancing themselves from it. Overall, the antonyms for "am offing" all suggest staying or becoming more involved in a situation rather than departing from it.