anomalous
/ə-ˈnä-mə-ləs/
adjective
inconsistent with or deviating from what is usual, normal, or expected : irregular, unusual
of uncertain nature or classification
marked by incongruity or contradiction : paradoxical
Researchers could not explain the anomalous test results.
irregular anomalous unnatural mean not conforming to rule, law, or custom. irregular implies not conforming to a law or regulation imposed for the sake of uniformity in method, practice, or conduct. anomalous implies not conforming to what might be expected because of the class or type to which it belongs or the laws that govern its existence.
noun
a mysterious phenomenon (especially an unidentified aerial phenomenon) that is sometimes assumed to be a spaceship from another planet : UAP —used especially as an alternative to UFO or unidentified flying object