Pig iron
WordNet
noun
(1) Crude iron tapped from a blast furnace
WiktionaryText
Etymology
In the 1800s, one method of iron-making involved pouring molten iron into molds in sand beds fed from a common channel. The resulting blocks of iron were called the suckling "piglets", and the channel was called the "pig". Since then, "pig iron" has become a widely used term.