huumus, pruun või must amorfne keeruka koostisega orgaaniliste ühendite kompleks, mis moodustab mulla orgaanilise aine põhiosa ja on keemilises seoses mulla mineraalosaga
vegetable mould; the dark-brown or black substance resulting from the slow decomposition and oxidization of organic matter on or near the surface of the earth, which, with the products of the decomposition of various rocks, forms the soil in which plants grow