Colluvium refers to material that accumulates at the base of a slope or hill, usually due to gravitational pull. Synonyms for this term include alluvial deposits, debris, sediment, and scree. Alluvial deposits, as the name suggests, is material that has been carried by a river or stream and deposited along its banks. Debris refers to any type of material that has been broken and tossed around, while sediment is a general term used to describe any type of material that gets deposited in water. Scree is a term used to describe smaller rocks and stones that often accumulate at the base of a slope. Overall, these terms help geologists better understand the different types of material that make up colluvium and how they form.