Grammaticalness is a term that describes the quality or state of being grammatical. While there may not be direct synonyms for this specific word, there are alternatives that can convey similar meanings. One such synonym is "correctness", which emphasizes the accuracy and adherence to grammatical rules. Another possible synonym is "accuracy", which highlights the precision and exactness in grammar usage. Additionally, "properness" can be used to denote the appropriateness and suitability of grammar. In essence, these synonyms aim to capture the concept of grammaticalness by highlighting the importance of correctness, accuracy, and properness in language usage.