digress
verb [intransitive] (formal)to start to talk about something that is not connected with the main point of what you are saying 离题；偏离主题 To digress for a moment, I would like to remind you that there will be no classes next week. 题外话一会儿，想提醒大家，下周不上课。
Word Originearly 16th cent.: from Latin digress- ‘stepped away’, from the verb digredi, from di- ‘aside’ + gradi ‘to walk’.