To move away from the main subject you are writing or talking about and to write or talk about something else. (Cambridge Dictionary)
To turn aside especially from the main subject of attention or course of argument. (Merriam – Webster)
If you digress, you move away from the subject you are talking or writing about and talk or write about something different for a while. (Collins Dictionary)
Leave the main subject temporarily in speech or writing. (Oxford Dictionaries)
What is the opposite word for Digress?
How to use digress in a sentence.