Meaning of lobster-tail helmet

lob'ster-tail hel"met

Pronunciation: (lob'stur-tāl"), [key]
— Armor. Armor.
  1. a burgonet fitted with a long, articulated tail of lames for protecting the nape of the neck, worn by cavalry in the 17th century.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.