The characteristic that most distinguishes arthropods from other invertebrates is their exoskeleton.

Here's why:

* Exoskeleton: Arthropods have a hard, external covering called an exoskeleton made of chitin. This provides them with structural support, protection from predators, and helps prevent water loss.

* Other Invertebrates: Most other invertebrates lack this rigid external covering. Instead, they may have soft bodies, shells, or other forms of protection.

While other features like jointed appendages and segmented bodies are also important, the exoskeleton is the defining trait that sets arthropods apart.