noun

• (countable) A device for capturing or killing mice and other rodents.
• (countable, Internet) A website designed to open another copy of itself when the user tries to close the webpage. Frequently used by advertisers and pornographers.
• (chiefly British, informal, uncountable) Ordinary, everyday cheese.
• (New Zealand) A slice of bread or toast topped with cheese and then grilled or microwaved.

verb

• (figuratively) To trap; to trick or fool (someone) into a bad situation.
  "He hoped to bring the rebels out of their trenches for a showdown battle somewhere south of the Wilderness, that gloomy expanse of scrub oaks and pines where Lee had mousetrapped Joe Hooker exactly a year earlier."
• (Internet, transitive) To prevent (the user) from leaving a website by opening another copy when it is closed.
  "The scammer is paid for each new visitor directed to his site. There is nothing wrong except that the user finds it impossible to leave the site because he is mousetrapped."