Chapeau \Cha`peau"\, n.; pl. Chapeux. [F., fr. OF. chapel hat. See Chaplet.]

1. A hat or covering for the head.

2. (Her.) A cap of maintenance. See Maintenance.

Chapeau bras[F. chapeau hat + bras arm], a hat so made that it can be compressed and carried under the arm without injury. Such hats were particularly worn on dress occasions by gentlemen in the 18th century. A chapeau bras is now worn in the United States army by general and staff officers.

Source: Webster's Revised Unabridged Dictionary (1913)