With all its variations, what does the term “Celadon” even mean?
There are various theories as to why Westerners started using the term “Celadon”. Regardless, “Celadon” refers to a category of Chinese ceramics known as 青瓷 (qing ci). 瓷 is porcelain while the 青 (qing) in 青瓷 signifies a color (or range of colors). But exactly which color is frequently debated. Ask a random person on the street in China what color is 青, and you may hear answers ranging from green to blue. Some might even say that 青 could represent black! Entire essays have been written about 青 by linguists and color theorists. In “On ‘Qing’” (《说“青”》), the Japanese sinologist Shigeru Shimizu (清水茂) describes the evolution of 青 by analyzing historical texts, and he concludes that 青 represents a hue from green to blue. But this range of hues can be modified in saturation and brightness (hence, black).
In ceramics, the colors resulting from a glaze containing small amounts of iron oxide fired in a reduction atmosphere perfectly falls within the spectrum of color represented by 青. From light to dark green and light to dark blue, all the colors of Celadon can be described as 青. So 青瓷 (qing ci) is a perfect term for this category of glaze.