ventail

noun

ven·​tail ˈven-ˌtāl 

: the lower movable front of a medieval helmet

Word History

Etymology

Middle English ventaile, borrowed from Anglo-French ventaille, from venter "to blow, fan" (derivative of vent "wind," going back to Latin ventus) + -aille, deverbal and denominal suffix, originally collective (going back to Latin -ālia -al entry 2) — more at wind entry 1

First Known Use

14th century, in the meaning defined above