The word ‘stereotype’ comes from the French adjective stéréotype, which itself comes from the Greek στερεός (solid) and τύπος (type). It was originally a term used in letterpress printing, referring to a solid plate of metal cast from a mould taken of a forme (a body of type secured in a metal frame for printing). In other words, a stereotype is a solid metal copy made of the original type. Then, while the copy is used for the actual printing, the letters in the original type are free to be used elsewhere. When it was introduced, this practice drastically increased printers’ efficiency and production.
Later on, ‘stereotype’ acquired the new meanings: ‘a widely held but fixed and oversimplified idea or image of a particular type of person or thing’ and ‘a person or thing that conforms to a stereotypical image’.
It’s not hard to see a connection: the modern word is like the printing word in that it, too, refers to a ‘fixed image’. (It goes without saying, however, that not every person identifies with these fixed images that are intended to describe them!)
Another similar word in English had its beginnings in printing as well: cliché. This originally French word was first used to refer to a stereotype or other plate used for printing an image. Interestingly, ‘cliché’ is ultimately onomatopoeic, representing the sound of a mould coming into contact with molten metal.
Today it most often means ‘a phrase or opinion that is overused and betrays a lack of original thought’. With this in mind, it seems pretty ironic that while clichés are typically reviled in writing, the concept has historically been linked to a practice – printing – that helped the written word and indeed, literacy, become widespread in the first place.