What does mould mean?
Mould is a versatile English word with two especially important meanings. As a noun, it refers to a soft, fuzzy growth of fungi that can appear on food, wood, fabric, walls, and other damp or organic surfaces. The related sense of a shaped form or cavity is used in manufacturing, sculpture, and crafts, where material is poured or pressed into a mould to create an object. As a verb, mould means to shape or form material by this process, and it can also mean to become covered or spoiled by fungal growth. The word is especially associated with the British spelling, while American English generally uses mold. Mould can suggest decay or deterioration when it refers to fungi, but in artistic and industrial contexts it is neutral and technical. Its ability to describe both a biological growth and a tool for making objects makes it an unusually memorable example of how one word can develop closely related but distinct senses.
A soft, fuzzy growth of fungi, especially on food, damp walls, wood, or fabric; also, a shaped form or cavity into which material is cast or pressed.
"The architect designed a mould that could reproduce the stone moulding precisely."
In the fungal sense, the word is commonly used in connection with food, buildings, and damp materials. In the manufacturing sense, it is often paired with 'cast' or 'moulding'.
To shape or form something by pressing or casting it in a mould; also, to become covered or spoiled by mould.
"The sculptor moulded the plaster into a detailed relief."
The transitive meaning 'shape or form' is generally more common than the intransitive meaning 'become covered in mould'.
The plural moulds is used for multiple fungal growths or, more commonly, for separate forms or cavities used in casting and shaping.
"The factory cleaned the moulds between each production run."
Mould has a double life: it names both the fuzzy fungus that can spoil food and the tool that gives objects their shape.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does mould come from?
The fungal sense of mould is generally traced through Old French to Latin molle, meaning a soft or moldy mass and related to mollis, 'soft'. From this Latin family come English words such as mild, mollify, mollification, and emollient, which reflect the idea of softness. The sense of a form or cavity used for shaping comes through a separate historical development from words associated with modelling and Latin modulus, a diminutive of mensura, 'measure'.
Related word forms
How mould is actually used
Mould is the standard British spelling; mold is standard in American English. The spelling distinction applies to both the fungal sense and the sense of a form used for casting. The verb meaning 'become covered in mould' is intransitive and is less common than the transitive meaning 'shape or form'.
Easily confused with mould
Mould and mold are the British and American spellings, respectively, of the same word.
Mould is a general term for fungal growth, while mildew usually refers specifically to the pale or dark fungal growth that develops on damp surfaces and plants.