Noun, plural patellas or patellae
Also know as the kneecap or kneepan.
1. a thick flat triangular movable bone that forms the anterior point of the knee, protects the front of the joint, increases the leverage of the quadriceps, and is usually regarded as a sesamoid bone since it is developed in the tendon of the quadriceps and in structure is similar to other sesamoid bones. (merriam-webster.com)
2. The sesamoid bone of the knee; the kneecap. (wiktionary.org)
3. A dish-shaped anatomical formation. (freedictionary.com)
Word origin: From Latin patella “pan, kneecap,” diminutive of patina “pan”. So called from its shape.