When someone makes a statement or claim that is not in agreement with the facts and is exagerated for effect. Usually to support an agenda. Useful in Journalism, Politics, and Court Cases. Is occasionally used here.

Example:

Could this please be moved to another page, one that already exists? We already have a million WikiOnWiki pages as it is. -- FrancisHwang

OverStatement? -- less than 20000 total pages exist and so the possibility that not only all of the pages, but 980000 pages that do not exist are on the subject of WikiOnWiki.