Which of the following best defines "machining"?

The definition of "machining" refers specifically to the process of shaping materials by removing material. This is a fundamental concept in manufacturing and tooling, where precision and control over the material are paramount. Machining typically involves various techniques such as turning, milling, drilling, and grinding, which can be performed on metals, plastics, and other materials to achieve desired dimensions and surface finishes.

In machining, tools are used to cut away material from a workpiece to create specific shapes and features, making it essential for producing intricate components with tight tolerances. This process also allows for enhancements in the mechanical properties of the finished product, such as increased strength or improved aesthetics.

The other options do not accurately reflect the definition of machining. For instance, increasing a material's temperature pertains to processes like heat treatment rather than shaping through removal. Testing material strength is related to material science and engineering but does not involve altering the material itself in the way machining does. Combining different materials would refer to methods like welding or adhesive bonding, which are entirely distinct from the machining process. Thus, the correct definition hinges on the essential characteristic of machining as a means of shaping through material removal.