What is the German term for "shackle"?

The correct term for "shackle" in German is "Schäkel." This word specifically refers to the U-shaped device used in various mechanical and maritime applications to connect chain links, cables, or other components securely. In German, "Schäkel" is widely recognized in engineering and nautical contexts for its precise meaning related to security and fastening.

The other terms listed do not relate to the concept of a shackle. "Dichtmasse" means sealant, typically used in construction or automotive contexts; "Passcheibe" refers to a spacer or washer, often used in machinery to provide spacing; and "Heißgeschirr" translates to hot dishes, which doesn't pertain to mechanical connections. Thus, "Schäkel" is clearly the appropriate choice.