: to turn aside especially from the main subject of attention or course of argument.

What does it mean when someone says digress?

I digress is a phrase used when someone realizes they've been rambling … for a long time … about something that isn't even relevant to the original question or topic.

How do you use I digress?

Digress is a verb. To digress means to temporarily wander or stray from your original plan or thought. You use 'digress' in a sentence (in both speaking and writing) to tell the listener or reader that you've left your topic but are trying to get back to it. 'Digress' is not often used, as it sounds formal.