What does compost mean?
Compost is a rich, dark substance made from decomposed organic material such as vegetable peelings, leaves, grass clippings, and other plant waste. Gardeners and farmers use it as a natural fertilizer and soil conditioner because it improves soil structure, retains moisture, and supplies nutrients that help plants grow. The word also functions as a verb: to compost something means to allow it to rot down deliberately so that it becomes this useful material. Composting has become closely associated with environmental sustainability, since it diverts food and garden waste away from landfills and reduces methane emissions. The word derives from Old French 'composte', ultimately from Latin 'composita', meaning things put together — a fitting origin for a substance formed by combining many materials into one. Today, compost appears frequently in everyday speech about gardening, recycling, and green living.
A mixture of decayed organic matter, such as plant remains and food scraps, used as fertilizer and soil conditioner.
"Add a layer of compost to the flowerbeds each spring."
In American English, compost often refers to the finished product as well as the decaying material itself; in British English the distinction between a compost heap and mature compost is sometimes drawn more explicitly.
To convert organic material into compost through controlled decomposition, typically by collecting and layering it in a heap or bin.
"They compost all their kitchen scraps instead of throwing them away."
The plural is rare and appears mainly in technical or agricultural writing referring to different types or batches of composted material.
"The trial compared several leaf-based composts for their nutrient content."
The word 'compost' comes from the same Latin root as 'compose' — because compost is quite literally composed of broken-down things put back together into new life.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of compost
Compost entered English in the late Middle Ages via Old French 'composte', meaning a mixture or composition. The French term ultimately traces back to Latin 'composita', the feminine past participle form related to 'componere' ('to put together'). This same Latin root gives English cognates such as compose, composite, component, and compound. The modern gardening sense — decayed matter used to enrich soil — became established by the early modern period and remains the dominant meaning today.
Related word forms
How compost is actually used
Common in both British and American English, especially in gardening, agriculture, and environmental contexts. The verb form is standard but slightly less frequent than the noun.
Easily confused with compost
Compote is a sweet dessert of stewed fruit, while compost is decayed organic matter used to enrich soil.
Composite is an adjective or noun describing something made of multiple parts, whereas compost is specifically decomposed organic material for soil.