casque

noun3

1. •
   A helmet.
2. •
   A hard structure on the head of some birds, such as cassowaries, some hornbills and guineafowl, and some reptiles such as chameleons and basilisks.

   • Helmeted Hornbill, Rhinoplax vigil (CR): Restricted to the Thai-Malay Peninsula, Sumatra and Borneo, this is the only hornbill species whose casque is solid keratin and therefore carvable. — 2015
3. •
   Synonym of galea.