What is the German term for 'joint'?

The German term for 'joint' is "Gelenk." This word specifically refers to the anatomical joint in the body where two or more bones meet, allowing for movement. In various contexts, "Gelenk" can be used to describe the physical joint in a body as well as joints in mechanical contexts, such as connections in machinery.

The other choices present terms that do not relate to the concept of a joint. "Längs" translates to "longitudinal," which refers to a direction rather than a connecting point. "Schnittstelle" means "interface," commonly used in technology or computing to describe a point of interaction between systems or components, not a joint. "Lesbarkeit" translates to "readability," which pertains to how easily something can be read or understood, unrelated to anatomical or mechanical joints.

Thus, the choice "Gelenk" is indeed the correct term for 'joint' in German.