Merriam-Webster Collegiate Dictionary - navicular

 I. adjective  Etymology: Middle English ~e, from Latin navicula boat, diminutive of navis  Date: 15th century  1. shaped like a boat a ~ bone  2. of, relating to, or involving a ~ bone ~ disease  II. noun  Etymology: New Latin (os) ~e a ~ bone  Date: 1816 a ~ bone:  a. one situated on the big-toe side of the tarsus in humans — called also scaphoid  b. scaphoid 2  c. one situated in the hoof of a horse behind the coffin bone