1. A departure from what is considered to be the ordinary type: The story, "The Elephant Man", recounts the life of a person with a severe abnormity.
2. An irregularity or monstrosity: The veterinarian recognized the abnormity of the birth of the calf when he saw that it had two heads.

In the past, traveling circuses often featured people and animals with abnormities which attracted the audiences into the special exhibitions.