The Collaborative International Dictionary of English v.0.48:

Dilation \Di*la"tion\, n. [L. dilatio. See Dilatory.]
   Delay. [Obs.] --Bp. Hall.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dilation \Di*la"tion\, n. [From dilate, v., cf. Dilatation,
   Dilator.]
   The act of dilating, or the state of being dilated;
   expansion; dilatation. --Mrs. Browning.
   [1913 Webster]

         At first her eye with slow dilation rolled. --Tennyson.
   [1913 Webster]

         A gigantic dilation of the hateful figure. --Dickens.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dilation
    n 1: a lengthy discussion (spoken or written) on a particular
         topic
    2: the act of expanding an aperture; "the dilation of the pupil
       of the eye" [syn: dilation, dilatation]