This noun denotes flint or hard stone, appearing only in Isaiah 5:28. The prophet uses it in a simile describing the Assyrian army's readiness—their horses' hoofs are hard 'like flint.' This comparison emphasizes strength, durability, and perhaps the ability to strike sparks. Flint's hardness made it valuable for both tools and metaphorical imagery. Some suggest reading it as 'rock' more generally, but 'flint' captures the specific connotation of exceptional hardness and the capacity to endure without wearing down.