1. fine sediment (such as silt, clay, or sand) deposited by running water, especially during floods
Usage: geology, earth science

Examples

• The river deposited layers of alluvium across the floodplain.
• Farmers value the rich alluvium left behind after seasonal floods.
• Geologists studied the alluvium to understand the region's geological history.
• The alluvium in the delta is composed mainly of fine sand and clay.
• Over centuries, alluvium built up to form fertile soil in the valley.
• The excavation revealed ancient artifacts buried in the alluvium.