In-commensurateness refers to the lack of a measurable or proportionate relationship between two things. The antonyms for this word are commensurateness and proportionality, which both indicate a balanced or equal relationship between two things. Conversely, words such as disparity, inequality, and imbalance can also be considered antonyms for in-commensurateness, as they suggest a lack of balance or fairness. Other antonyms for in-commensurateness may include adequacy, sufficiency, and compatibility, which convey the idea that two things are suitable or appropriate for each other. Ultimately, the antonyms for in-commensurateness are words that indicate a sense of harmony, balance, or proportion between two things.