rotula /rotˈū-lə/

1. The knee-cap (anatomy)
2. A radial piece of Aristotle's lantern in sea-urchins (zoology)

• black pepper
• blackpoll
• blackpolls
• Black Pope
• black powder
• Black Power
• black pudding
• black puddings
• black quahog
• black-quarter
• black rat
• black rats
• black rhinoceros
• black rhinoceroses
• black robin
• black robins
• Black Rod
• black rot
• Black Russian
• blacks
• black salsify
• black sheep
• Black Shirt
• Blackshirt
• black skipjack