The antonyms for the word "most sharing" can vary depending on the context in which it is used. For example, if it refers to a person who is unwilling to share, the antonyms could be selfish, greedy, or stingy. On the other hand, if it is a reference to a social media post that has received few shares, the antonyms could be unpopular, unnoticed, ignored, or unremarkable. Additionally, if it is related to a business that hoards information, the antonyms could be secretive, uncooperative, or possessive. Regardless of the context, it is clear that the opposite of "most sharing" implies withholding or lacking in generosity.