A sticky thread is a thread that is not slippery. That is, no matter how many threads have been created after this one, it will always remain at (or near) the top of the list. These threads are usually either the most popular, or state general information that everyone should know about the board. Usually it is a good idea to check the sticky threads when you first come across a board.
A metric that refers to the capacity of a site or an ad to maintain a visitor's attention (page views or minutes per page) for an extended period of time. Chat rooms and games have traditionally been considered high "sticky" content, as well as financial services sites that offer calculators and worksheets.
A website quality referring to the amount of time a visitor stays at the site. A sticky site is one with longer than average visit times. An average web page visit is five minutes.
"Sticky" refers to the ability to increase user retention time. Sticky sites are those where the visitors stay for an extended period of time. For instance, a banking site that offers a financial calculator is stickier than one without it because the user is inclined to spend expended periods using the calculator.