Obsidian is a dark, glass-like volcanic rock that is formed from lava. It is typically shiny and depending on its chemical composition, can have colors ranging from black to dark green. When we think of obsidian, we often think of strength, durability, and toughness. However, if we were to look for antonyms for "most obsidian," we would find words that describe the opposite characteristics. These antonyms could include words like fragile, weak, delicate, and brittle. While obsidian may not have many synonyms, its antonyms reflect its contrasting properties and offer a means of describing other materials and substances that are dissimilar to obsidian.