Incommutable is an adjective that means unable to be changed or altered. Some synonyms for this word are immutable, unchangeable, fixed, and constant. Immutable connotes something that is permanent and unalterable, while unchangeable implies an incapability to be moved or modified. Fixed suggests a position or state that is unmovable or unalterable, and constant denotes a condition that remains unchanged or stable. Other related synonyms for incommutable include rigid, inflexible, and set, all of which describe something that cannot be adjusted, modified, or changed. These synonyms convey a sense of permanence and stability, which can be applied to various contexts.