Definition of Closing Line

What does the term "closing line" mean in the world of sports betting? What is meant by a "closing line"?

The "closing line" represents the final resting place of odds before the betting on a sporting event closes.

For instance, let's say that Anderson Silva is fighting Chris Weidman for the UFC Middleweight title.

The line opens up like this:

Anderson Silva, -300
Chris Weidman, +240

However, by the time that betting for the fight closes, the odds look like this:

Anderson Silva, -250
Chris Weidman, +200

As you can see, the odds moved in Weidman's favour while the odds where open to the general public.

The "closing line" for this fight would be Silva -250/Weidman +200, as this is what the odds where at when betting for the fight was halted.