If something is compostable, you can turn it into compost: mix it with garden waste, let it break down, and get a dark, useful soil-like stuff for plants. You see the word on packaging, cups, and bags that want to sound kind to the earth. Though actually, it is stricter than biodegradable. Biodegradable only says a thing will break down someday, somewhere. Compostable says it will break down in compost conditions and leave something that helps soil, not bits of plastic. Packages sometimes add a second split: home-compostable (your garden heap) versus industrial-compostable (a hot factory heap). A cup can wear a green label and still not belong in a backyard pile. As a noun, people say compostables for the things themselves.

可堆肥的