Exactment is a relatively uncommon word, and as such, there are not many direct synonyms. However, depending on the specific context in which the word is used, there may be other phrases or words that could be used in its place. For example, if exactness is the key attribute being described, then synonyms such as precision, accuracy, or meticulousness could be used. Alternatively, if the word is being used more broadly to describe the enforcement of rules or the imposition of penalties, then synonyms such as enforcement, imposition, or punishment may be appropriate replacements. Ultimately, selecting an appropriate synonym for exactment will depend on the specific context and meaning that the word conveys.