rotula /rotˈū-lə/

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

• airports
• air-power
• air-powers
• air-propeller
• airprox
• air-pump
• air-pumps
• air quotes
• air rage
• air rages
• air-raid
• air-raids
• air-rail
• air-rails
• air rifle
• air rifles
• airs
• air-sac
• air-sacs
• airs and graces
• Air Scout
• airscrew
• airscrews
• air-sea rescue
• airshaft