1) Any armor for the head 2) French word used in English 3) Helmet 1) Casquet 2) Casquetel 3) Galea 
The head or crest of an animal
Casque is a French word for helmet. It can refer to: ...
helmet
• (n.) A piece of defensive or ornamental armor (with or without a vizor) for the head and neck; a helmet.
An enlargement of the back surface of the upper bill of a hornbill bird.
Growth above bill of hornbills.
Casque noun [ French casque , from Spanish casco See Cask .] A piece of defensive or ornamental armor (with or without a vizor) for the head and neck; a helmet. « His casque overshadowed with brilliant plumes. Prescott. » 
The Casque was a French Le Hardi Class destroyer (torpilleurs) of 1772 tons displacement launched in 1938. The Casque had a top speed of 37 knots, a range of 9600 km at 15 knots and carried a complement of 175. Armaments consisted of six 5.1-inch guns; four 37 mm anti-aircraft guns; four 13 mm anti-aircraft guns and seven 21.7 inch torpedo tubes.
[n] - (15-16th century) any armor for the head
Growth above bill of hornbills
noun (15-16th century) any armor for the head; usually ornate without a visor
the upward projection at the back of chameleon's head.
Horny ridge on upper mandible of horn bills.