poleyn
/ˈpɒleɪn/ /ˈpɒlɪn/Armour. Now historical
noun
A piece of armour covering and protecting the knee, fastened to the thigh-piece.
Origin
Late Middle English; earliest use found in Inquisition Miscellany. Apparently from Anglo-Norman polein knee-piece, of unknown origin. Perhaps compare poulaine.