pig-iron

The term 'pig-iron' is a vivid example of industrial metaphor. The word 'pig' has ancient Germanic roots, originally referring to a young swine. In the 17th century, this term was applied to the crude iron produced in a blast furnace. The logic stems from the method of casting: the molten iron was channeled from a main runner (the 'sow') into a series of parallel, smaller molds laid out in sand, which resembled a litter of piglets suckling. Thus, the 'pigs' were the individual ingots. 'Iron' itself has a deep history, tracing back through Old English and Proto-Germanic to a likely Celtic source, referring to the hard, strong metal. The compound 'pig-iron' therefore literally means "iron cast in the shape of pigs," preserving a snapshot of historical foundry practice in its modern, purely technical meaning.

Structure: pig (young swine) + iron (metal element) pig: From Middle English 'pigge', of uncertain origin, possibly from Old English picga. In this compound, it functions as a metaphorical descriptor based on shape or process. iron: From Old English 'īsern', 'īren', from Proto-Germanic īsarną, ultimately from Proto-Celtic īsarnom. It functions as the core noun denoting the metallic element.