In-commensurate refers to something that is not proportional or is not in harmony with something else. The antonyms for in-commensurate are proportional, adequate, reasonable, and fitting. Proportional means corresponding in size, amount, or degree. Adequate means enough or satisfactory for a particular purpose. Reasonable means being sensible or fair in judgment. Fitting means appropriate or suitable in the circumstances. These antonyms indicate a state of being or a relationship that is balanced and harmonious. In essence, they are the opposite of in-commensurate and suggest a sense of coherence, consistency, or balance.