Moulder/ˈməʊldər/ Definition 1 of 2Pro Tip 1/3Physical Decay Used to describe the natural decomposition of things, typically food or organic material. The old pumpkin began to moulder on the porch. Pro Tip 2/3Not Instant Indicates a gradual process, not something that happens quickly. The loaf of bread will slowly moulder if left uneaten. Pro Tip 3/3Visible Change The effects of moldering are often visible, such as mold growth or disintegration. As the leaves moulder, they blend back into the earth.