Mouldy/ˈməʊldi/ Definition 1 of 3Pro Tip 1/3Visible Growth Mouldy refers to visible spots or layers caused by fungal growth, often green, black, or white. She tossed the mouldy strawberries in the trash. Pro Tip 2/3Food and Objects Commonly found on old food and damp surfaces or objects left in moist environments. I need to clean the mouldy shower curtain. Pro Tip 3/3Negative Connotation The term often implies something is spoiled, unclean, and should be discarded. No one wants to eat mouldy fruit.