A cauliflower ear is one that is permanently damaged and disfigured because it has been hit many times. Seen especially on veteran boxers or rugby players.
A cauliflower ear is so called because it looks a little like cauliflower, the vegetable (as shown in the photo).
Examples of use:
1. That old man has a cauliflower ear. Perhaps he used to be a boxer.
2. I got this cauliflower ear as a young man because I used to fight a lot.
Image by Muffet