Antonyms for the word "most contributing" can include "least contributing," "unproductive," "least effective," "non-contributing," and "unhelpful." These words describe something that does not add value, support, or assistance to a cause or task. It can also connote a lack of engagement, interest, or involvement. In contrast to the word "contributing," which highlights someone or something's active participation or impact, the antonyms emphasize the opposite, implying that someone or something is detracting or hindering from a desired outcome. It is important to consider both sides of the spectrum when evaluating the performance or impact of an individual or organization.