incompatible

This term describes a fundamental clash between two entities, whether they are human temperaments or technical specifications. It suggests a state of mutual exclusion where the presence of one prevents the successful operation or coexistence of the other. In interpersonal contexts, it carries a heavy connotation of inevitable conflict or failure, often used to describe the breakdown of romantic relationships or professional partnerships.

In technical environments, the word shifts toward a neutral, descriptive tone. It refers to a lack of standardization or a mismatch in protocols, such as a hardware plug that does not fit a socket or software that cannot run on a specific kernel. Unlike "different," which is neutral, "incompatible" implies a functional failure resulting from those differences.