Casque — a helmet, or a helmet-like structure — comes from French casque, from Spanish casco (helmet, skull), and is on record since before 1586. It opens A.Word.A.Day’s “A change of character: Act I” week, illustrated by an 1869 Gould and Richter plate of an Australian cassowary, whose casque is the crest on its head; one 2013 Cairns Post keeper notes a young bird’s is “about two and a bit inches tall already.”