The Collaborative International Dictionary of English v.0.48:

Headpiece \Head"piece`\ (-p[=e]s`), n.
   1. Head.
      [1913 Webster]

            In his headpiece he felt a sore pain. --Spenser.
      [1913 Webster]

   2. A cap of defense; especially, an open one, as
      distinguished from the closed helmet of the Middle Ages.
      [1913 Webster]

   3. Understanding; mental faculty.
      [1913 Webster]

            Eumenes had the best headpiece of all Alexander's
            captains.                             --Prideaux.
      [1913 Webster]

   4. An engraved ornament at the head of a chapter, or of a
      page.
      [1913 Webster]

WordNet (r) 3.0 (2006):

headpiece
    n 1: the band that is the part of a bridle that fits around a
         horse's head [syn: headstall, headpiece]
    2: a protective helmet for the head