boulder

This term describes a rock of significant size, often evoking images of rugged landscapes, riverbeds, or glacial deposits. It carries a connotation of heaviness and permanence, distinguishing it from smaller stones or pebbles by its sheer mass and often rounded edges caused by natural weathering. In a geological sense, the word specifically refers to fragments larger than 256 millimeters in diameter. While it is a standard countable noun, it is frequently used in the context of outdoor activities like bouldering, where the focus is on the physical challenge of climbing these specific types of rock formations.