What is the German term for 'to lubricate'?

The German term for 'to lubricate' is indeed "schmieren." This word specifically refers to the act of applying a lubricant to reduce friction between surfaces, which is a crucial process in various mechanical and technical applications. Lubrication ensures that moving parts operate smoothly and can extend the life of machinery by minimizing wear and tear.

In contrast, the other choices do not pertain to the action of applying lubricant. For instance, "aufblasen" translates to 'to inflate,' which involves adding air to an object. "Sicherungsdraht" means 'safety wire,' a term used in securing mechanical components, and "leck" refers to a 'leak,' indicating the escape of a substance, often fluid, from a container. These terms are distinct and serve different functions in both language and application, thus highlighting why "schmieren" is the correct choice when referring to lubrication.