What term describes things that are touching or joining at the edge or boundary?

The term that describes things that are touching or joining at the edge or boundary is "contiguous." This word specifically signifies that two or more entities are in direct contact with one another, sharing a common edge without any separation. In various contexts, such as geography, law, or computer science, the concept of contiguity emphasizes the importance of proximity and connection between entities.

For instance, in geographic terms, contiguous land refers to parcels of land that are next to each other without any intervening spaces. In the context of data, contiguous memory refers to blocks of memory that are stored sequentially without gaps.

While "adjacent" also means neighboring or next to, it does not inherently imply that there is a physical connecting edge or that the items are touching. Similarly, "connected" may indicate a broader sense of linkage that doesn’t specifically focus on the idea of being right next to each other at their boundaries. "Convergent" generally describes the process of moving toward a common point, which differs from the idea of edges meeting. Therefore, "contiguous" accurately captures the concept of being in direct contact or sharing boundaries.