Anomaly: A deviation from the usual, something different, peculiar, or abnormal.

A congenital anomaly is something that is unusual and different at birth. A minor anomaly in this context is defined as an unusual anatomic feature that is of no serious medical or cosmetic consequence to the patient. A minor anomaly of the feet might, for example, be curvature of the second toe so it overlaps the third toe a little. By contrast, a major anomaly might be a cleft lip and palate, a birth defect of serious medical and cosmetic consequence to the patient.

"Anomaly" comes from the Greek word "anomalos," which means "uneven" or "irregular." "Anomalos" comes from the prefix "a-" (meaning "not") and the word "homalos" (meaning "even").