The phrase "most hundred to one" implies a very high probability or likelihood of something happening. Its antonyms would be words or phrases that indicate a lower probability or likelihood of something occurring. Some antonyms of "most hundred to one" include "unlikely," "doubtful," "improbable," "not a chance," "remote," "unfeasible," "impossible," "rare," and "outlandish." These words indicate that something is not very likely to happen, whereas "most hundred to one" suggests that it is practically a certainty. Using these antonyms in place of "most hundred to one" can help convey a different level of expectation or probability.