The Collaborative International Dictionary of English v.0.48:

Summity \Sum"mit*y\, n. [L. summitas, fr. summus highest: cf. F.
   sommit['e]. See Sum, n.]
   1. The height or top of anything. [Obs.] --Swift.
      [1913 Webster]

   2. The utmost degree; perfection. [Obs.] --Hallywell.
      [1913 Webster]