aventail

An aventail or camail is a flexible curtain of chainmail on a helmet, that extends to cover the neck and shoulders. The mail could be removed for cleaning or storage, and attached to the helm through use of a leather cord that was threaded through brass rings at the edge of the helm. Aventails were most commonly seen on bascinets in the 14th century and served as a replacement for a Chainmaille coif. Some aventails were decorated with edging in brass or bronze links, or dagged edges.
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Noun
1. a medieval hood of mail suspended from a basinet to protect the head and neck
(synonym) camail, ventail
(hypernym) hood
(part-holonym) basinet

(n.)
The movable front to a helmet; the ventail.
  

A skirt of mail attached to a bascinet or armet during the 14th and 15th centuries. It defends the neck from attack, usually hanging to at least 1" below the shoulder point for bascinets. Generally it was attached to a leather cuff that wrapped around the base of the bascinet and up the cheeks, which was pierced with holes and laced to the helmet through vervelles .