Bounce rate

The percentage of web site visitors who visit your web site and leave (bounce away) without getting any deeper into your site. 
Official WAA definition: Single page view visits divided by entry pages.

Related content:

Content Type: Article

Bounce Rate and Click-through Rate

What is Bounce Rate? (bouns rāt) n.

The bounce rate for the homepage, or any other page through which visitors enter your site, tells you how many people 'bounce' away (leave) from your site after viewing...

Content Type: Report page

Bounce Rate

Traffic quality may (or may not) be defined by how many people bounce off of a site after one or two clicks, or remain on the site. The report contains 4 columns; 
Bounce rate of visitors(% of total who bounce away)...