/moʊld/
[noun] A hollow container used to give a liquid or soft material a specific shape when it hardens; also a type of fungus that grows on old food or damp surfaces, forming a soft, fuzzy coating.
The word 'mould' actually comes from two completely different ancient words that just happened to sound the same over time.
The word 'mould' carries within it not one history but two — twin rivers of meaning that have flowed alongside each other for centuries, occasionally touching but never quite merging. The first meaning, the container used to shape things, and the second, the fuzzy fungus on forgotten bread, come from entirely separate origins, yet both have worn the same spelling for so long that we rarely stop to notice the coincidence.
The 'mould' that means a shaping form descends from the Old French word 'molle', which itself came from the Latin 'modulus', meaning a small measure or unit of size. 'Modulus' was a diminutive form of 'modus', meaning manner, measure, or method — a word that also gave English 'mode', 'model', 'module', and 'modify'. The Latin 'modus' → Old French 'molle' → Middle English 'molde' pathway brought with it the idea of something that sets the standard, that determines the shape of what comes after. A mould does not just contain — it defines. When we say someone was 'cast in a certain mould', we are reaching back, unknowingly, to this Roman sense of careful measure and form.
The 'mould' meaning fungus has an older and earthier story. It comes from Middle English 'mowlde', which derives from an early Scandinavian root connected to the Old Norse 'mygla', meaning to grow mouldy. Related forms appear in Middle Low German as 'mul' and in Old High German as 'mulm', both referring to rotting matter or dust. This family of words connects to a deeper Proto-Germanic root suggesting decay, crumbling, and the return of matter to earth. There is also a third sense of 'mould' — loose, crumbly earth or soil — which comes from Old English 'molde', meaning earth or ground, and this earthy word is a cousin of the fungal sense, both pointing back to the same ancient Germanic root of soft, decomposing matter.
All three senses arrived in written English at different moments. The soil meaning is the oldest, present in Old English texts before the Norman Conquest, used in poetic contexts such as describing a body returning to the earth. The shaping-container sense arrived in the 13th and 14th centuries, riding in on the wave of French vocabulary that followed the Norman Conquest of 1066. The fungus sense solidified in the 15th and 16th centuries, though its Germanic roots were always present beneath the surface of spoken language.
Over the centuries, 'mould' in its shaping sense grew richer in metaphor. By the 16th century, writers like Shakespeare were using it to talk about character and temperament — a person's 'mould' was their essential nature, the invisible form in which their personality had been poured. This metaphorical use has never entirely left us. When we admire someone who 'broke the mould', we are using an image from metalworking and pottery-making that is nearly a thousand years old. Meanwhile, the fungal mould — patient, quiet, and persistent — kept its humbler place in kitchens and cellars, a reminder that even the most carefully shaped things, left alone, will eventually return to something older and simpler.