The term "sub-altern" refers to a lower-ranking or subordinate individual or group. Antonyms for this word could include "dominant," "superior," "supreme," or "primary." These antonyms suggest a position of power and authority, rather than a subordinate one. Other potential antonyms could include "leader," "mainstream," or "central," which further emphasize the idea of being at the forefront or center of a given situation or hierarchy. Overall, considering antonyms for "sub-altern" can help to illuminate the nuances of power dynamics and social hierarchies within a given context.