Although there is a lot of variation among all the individual “dogs” in our experience, we can use the word dog to talk about any one of them as a member of the category. A category is a group with certain features in common and we can think of the vocabulary we learn as an inherited set of category labels. These are the words for referring to concepts that people in our social world have typically needed to talk about.

It is tempting to believe that there is a fixed relationship between the set of words we have learned (our categories) and the way external reality is organized. However, evidence from the world’s languages would suggest that the organization of external reality actually varies to some extent according to the language being used to talk about it. Some languages may have lots of different words for types of “rain” or kinds of “coconut” and other languages may have only one or two. Although the Dani of New Guinea can see all colors of the spectrum, they only use names for two of them, equivalents of “black” and “white.” The Inuit of Greenland have names for those two, plus red, green and yellow. English has names for those five colors, plus blue, brown, purple, pink, orange and gray. It seems that languages used by groups with more technology have more color terms. Observing this difference between the number of basic color terms in languages, we can say that there are conceptual distinctions that are lexicalized (“expressed as a single word”) in one language and not in another.