Digress, v. i. [imp. & p. p. Digressed; p. pr. & vb. n. Digressing.]
Etymology: [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. Moreover she beginneth to digress in latitude. Holland. 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.
2. To turn aside from the right path; to transgress; to offend. [R.] Thy abundant goodness shall excuse This deadly blot on thy digressing son. Shak.
1 other Webster entry under this spelling
Digress, n.
Digression. [Obs.] Fuller.
Shades of meaning
Fernald has no entry of its own for digress; he lists it under wander.
Where he writes about it:
To wander (AS. windan, wind) is to move in an indefinite or indeterminate way which may or may not be a departure from a prescribed way; to deviate (L. de, from, and via, a way) is to turn from a prescribed or right way, physically, mentally, or morally, usually in an unfavorable sense; to diverge (L. di, apart, and vergo, incline, tend) is to turn from a course previously followed or that something else follows, and has no unfavorable implication; to digress (L. di, apart, aside, and gradior, step) is used only with reference to speaking or writing; to err is used of intellectual or moral action, and of the moral with primary reference to the intellectual, an error being viewed as in some degree due to ignorance. — from wander