The Collaborative International Dictionary
Rotula
Rotula \Rot"u*la\, n. [L., a little wheel; cf. It. rotula.] (Anat.) The patella, or kneepan.
Wiktionary
rotula
n. (context skeleton English) The patella.
Usage examples of "rotula".
It’s a mobile rotula, like the ones Trithemius used for his coded messages.