1. A process that has been set up to accomplish a particular objective: "The company director developed a mechanism for generating more revenue."
2. A piece of machinery or a part or group of parts that have a particular function: "A can-opener is a simple mechanism used to open cans."

"Cameras have had shutter mechanisms that were used to take good pictures."

3. A system or process which is used to produce a particular result: "The legislature is still trying to come up with a legal mechanism to prevent lobbyists from having too much influence on government decisions."
4. Procedures for thinking or behaving that help or protect people in specific ways: "Local officials are making efforts to provide mechanisms that can help people who are suffering from the terrible results of the tornadoes that destroyed homes and seriously injured or killed family members."