ETYM Old Fren. compost, from Latin compositus, p. p. Related to Composite.
A mixture of decaying vegetation and manure; used as a fertilizer.

To convert to compost, as of organic debris.
Organic material decomposed by bacteria under controlled conditions to make a nutrient-rich natural fertilizer for use in gardening or farming. A well-made compost heap reaches a high temperature during the composting process, killing most weed seeds that might be present.
As the decomposers feed, they raise the temperature in the center of the compost as high as 66şC/150şF.