The Collaborative International Dictionary of English v.0.48:

Seigneurial \Seign*eu"ri*al\ (s[=e]n*[=u]"r[i^]*al), a. [F., fr.
   seigneur. See Seignior.]
   1. Of or pertaining to the lord of a manor; manorial. --Sir
      W. Temple.
      [1913 Webster]

   2. Vested with large powers; independent.
      [1913 Webster]