A pauldron (sometimes spelled pouldron or powldron) is a component of
plate armour, which evolved from
spaulders in the 15th century. As with spaulders, pauldrons cover the shoulder area. Pauldrons tend to be larger than spaulders, covering the armpit, and sometimes parts of the back and chest. Pauldrons typically consists of a single large dome-shaped piece to cover the shoulder (the "cop") with multiple
lamés attached to it to defend the arm and upper shoulder. On armours designed for mounted combat, whether in the tournament or the field, the pauldrons would be usually be assymetrical, with one pauldron sporting a cut-away to make room for a lance-rest.
See more at Wikipedia.org...