main topic; main subject; main issue; main question
Refers to the central theme or point of a discussion, meeting, or piece of writing. Often used when moving from preliminaries to the core matter.
Let's stop the preliminaries and get to the main topic.
His talk always strays from the main subject.
this subject; the matter at hand
Used to refer back to the current topic under discussion, often in formal or written contexts. Less common than sense 1.
Please explain this subject in a little more detail.
The conversation strayed from the main topic.
Let's get back to the main topic now.
He nervously brought up the main topic.