Definitions for "noninterchangeable"
not able to be interchanged without changing the truth value.
Not able to be substituted for each other; -- of objects, such as parts of machinery; as, the ink cartidges on the new printer are noninterchangeable with those on the older model.
such that the terms of an expression cannot be interchanged without changing the meaning; "the arguments of the symmetric relation, `is the father of', are noninterchangeable"