The Collaborative International Dictionary of English v.0.48:

Factum \Fac"tum\ (f[a^]k"t[u^]m), n.; pl. Facta. [L. See
   Fact.]
   1. (Law) A man's own act and deed; particularly:
      (a) (Civil Law) Anything stated and made certain.
      (b) (Testamentary Law) The due execution of a will,
          including everything necessary to its validity.
          [1913 Webster]

   2. (Mach.) The product. See Facient, 2.
      [1913 Webster]