1. Fragmented particulate of organic matter, or very small pieces of natural matter, derived from the decomposition of plant and animal remains; organic trash: By the end of winter, there is a lot of organic detritus that has accumulated in the yard which requires the gardener to clean up before planting flowers.
2. Discarded material: A lot of detritus, thrown into rivers by people, end up on the banks of the water ways and there are some efforts made to clean such exposed areas by professionals and by volunteers who want to maintain a better environment.
3. In geology, matter produced by the wearing away of exposed surfaces, especially gravel, sand, clay, or other material eroded and washed away by an aqueous agency; a mass or formation of this nature: Glacial grit is rock detritus that is so finely pulverized that it is suspended in the water and will not settle or separate.
4. In ecology, the organic decomposition of plants and animals: The soft ground in the forest is considered to be part of the detritus caused by the breaking down of nonchemical matter.