atypical

This term describes a deviation from a standard pattern or a statistical norm. It carries a neutral to clinical tone, often used in medical, scientific, or academic contexts to identify an anomaly without necessarily labeling it as "wrong" or "bad." While "unusual" is a general term for something rare, "atypical" specifically emphasizes the lack of typical characteristics associated with a specific category or classification. It suggests a mismatch between an individual instance and the expected prototype of its group.