The word "more aftermost" refers to something that is located at the very back or end of a list or series. Its antonyms could include terms such as "frontmost," "foremost," "first," "initial," "beginning," "head," or "front." Alternatively, the opposite of "more" could be "less," "fewer," or "shorter," indicating a smaller number or quantity. Depending on the context, other antonyms could include words like "less important," "lower-ranked," or "inferior," indicating a lower status or significance. In summary, antonyms for "more aftermost" might describe something at the front, beginning, or with a smaller quantity, importance, or status.