What exactly is a robot?

What exactly is a robot?
I have to write a definition essay on something and I chose robot for the topic but I need a little more information on what a robot really is ie:name origin what makes it a robot etc.

According to the Robotic Industry Association (IRA) the definition of robot is the following:
“a robot is a re-programmable, multifunctional. manipulator designed to move material, parts, tool, or specialized devices, through variable programmed motions for the performance of a variety of tasks” (Jablonski and Posey 1985).

This definition is quite restrictive, excluding mobile robots, among other things. On the other extreme, another definition describes robotics as the intelligent connection of perception to action (Brady 1985). This seems overly inclusive but does acknowledge the necessary relationship between these essential ingredients of robotic systems.

Another good definition is : An intelligent robot is a machine able to extract information form its environment and use knowledge about its world to move safely in a meaningful and purposive manner (Arkin 1998).

Actually the term robot is applied to a great variety of mechanical devices, such as teleoperators, underwater vehicles, autonomous land rovers, etc. Virtually anything that operates with some degree of autonomy, usually under computer control, has at some point been called a robot.