The Collaborative International Dictionary of English v.0.48:

Signiorize \Sign"ior*ize\, v. t. [See Seigniorize.]
   To exercise dominion over; to lord it over. [Obs.] --Shelton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Signiorize \Sign"ior*ize\ (s[=e]n"y[~e]r*[imac]z), v. i.
   To exercise dominion; to seigniorize. [Obs.] --Hewyt.
   [1913 Webster]