Which word can be defined as "tool or technique used to do a task"?

Question

Quizplus · Accepted Answer

Device means "an object designed and manufactured to perform one or more functions".
Invention means "something that has been created or made up".
The light bulb is one of Thomas Edison's most famous inventions.
Motif means "primary or recurring theme". Specifically, a motif is repeated symbology throughout a work of literature or film.
An example of a motif is the color red in the movie the Sixth Sense. The color red is used throughout the film to foreshadow that something bad is about to happen.
Belief means "an opinion or something that a person holds to be true".
It is my belief that the world is flat.

Which Word Can Be Defined as "Tool or Technique Used