( informal , especially BrE ) used when you are going to say more about a subject that has already been mentioned :
Talking of Sue, I met her new boyfriend last week.
( informal , especially BrE ) used when you are going to say more about a subject that has already been mentioned :
Talking of Sue, I met her new boyfriend last week.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005