A device designed to catch
mice. There are several variant designs, both with and without
moving parts.
The simplest mousetrap is the spring-loaded type I'm sure we're all familiar with. A small rectangle of wood, with a metal bar with is held in place by springs. The trap is set by pulling the snap bar back onto the other half of the trap, and using the attached securer bar to latch into the pressure plate, holding the snap bar back. When a mouse comes after the bait on the pressure foot, it'll nudge it enough to release the securer bar. SNAP! Ideally, it breaks the mouse's neck, killing it instantly, but some mice are stupid, and end up positioned incorrectly on the trap. Perhaps the most economical style of mousetrap, as it is usually cheap initial purchase, and can kill many mice.
Another type is the glue trap. No moving parts here, but it's not reusable. Basically a very sticky pad, in the tradition of Brer Rabbit. Mouse walks on, sticks to the glue pad. This is inherently a live catch type of trap. After a mouse becomes entrapped, the entire trap is thrown away, mouse and all.
Another type of trap has been developed, the live catch mechanical trap. Basically a scaled down version of larger live catch traps, it consists of a hollow rectangular prism with one end being a movable door. To set this type of trap, the door is pressed upwards against the top of the trap until it latches into place. Some sort of bait is placed at the back end of the trap, behind the pressure plate. A curious mouse walks in, goes for the bait, and the door drops down behind it. For those so inclined, the thusly caught mouse can be released in the wilderness, to be eaten by some predator or another. The trap could conceivably then be used again, or the trap could be discarded in the same fashion as the glue trap.
Though not truly a trap, mouse poison produced the same desired result, namely no mice. Usually made of arsenic or other toxic compound, the poison is produced in little pellets, and somehow flavored to be attractive to mice. The little rodents eat the poison, with predictable results.