The Collaborative International Dictionary of English v.0.48:

Digress \Di*gress"\, n.
   Digression. [Obs.] --Fuller.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Digress \Di*gress"\, v. i. [imp. & p. p. Digressed; p. pr. &
   vb. n. Digressing.] [L. digressus, p. p. of digredi to go
   apart, to deviate; di- = dis- + gradi to step, walk. See
   Grade.]
   1. To step or turn aside; to deviate; to swerve; especially,
      to turn aside from the main subject of attention, or
      course of argument, in writing or speaking.
      [1913 Webster]

            Moreover she beginneth to digress in latitude.
                                                  --Holland.
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            In the pursuit of an argument there is hardly room
            to digress into a particular definition as often as
            a man varies the signification of any term. --Locke.
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   2. To turn aside from the right path; to transgress; to
      offend. [R.]
      [1913 Webster]

            Thy abundant goodness shall excuse
            This deadly blot on thy digressing son. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

digress
    v 1: lose clarity or turn aside especially from the main subject
         of attention or course of argument in writing, thinking, or
         speaking; "She always digresses when telling a story"; "her
         mind wanders"; "Don't digress when you give a lecture"
         [syn: digress, stray, divagate, wander]
    2: wander from a direct or straight course [syn: sidetrack,
       depart, digress, straggle]