不着边际 [- zhuó biān jì]not to the point; (of a talk) empty and impracticable; entirely irrelevant in a roundabout way; far-fetched; far off the mark; irrelevant; neither here nor there; not touch the edge; off the point; totally beside the point; wide of the mark:
•¶不着边际的长篇大话 long rambling talk
•¶不着边际的话 irrelevant talks
•¶ 他越讲越不着边际。 The more he talked, the further he strayed from the point.