What are open classes and closed classes? Some of the main classes of words, also known as parts of the speech, are nouns, verbs, adjectives, adverbs, pronouns, prepositions, numerals and conjunctions. If you think about nouns, you’ll come up with hundreds or thousands of examples right away. You also know that new nouns are created all the time with new inventions or notions that must be named. The same is true about some other classes, but not all of them. For example it’s rather impossible that a new conjunction or preposition appears in near future.
So, considering this criterion, we can divide all the classes into two groups: open classes and closed classes.
An OPEN CLASS is a class in which new words appear continuously. Here belong nouns, verbs, adjectives and adverbs. We not only create completely new words, but we also derive words from already existing words. There are some productive word formation processes in English that let you create verbs from nouns, adverbs from adjectives or nouns, adjectives from nouns, etc. Here are some examples:
1) There is a word formation process in which nouns denoting people are created from verbs by means of the ending –EE. So, a person who RETIRES is a RETIREE, for example.
2) Another process consists in creating adverbs from nouns by means of the ending –WISE. So, if something is done ELEMENT by ELEMENT, it’s done ELEMENTWISE.
3) You can also create verbs out of nouns by means of the ending –IZE. So, if you adapt something to a STANDARD, you STANDARDIZE it.
These are just a few examples, but the possibilities are endless.
On the other hand, a CLOSED CLASS is a class in which, unlike in open classes, new words do not appear at all or appear very slowly, like over tens of years or even centuries. The closed classes include auxiliaries, conjunctions and prepositions.
Let’s have a look at prepositions, for example. You know this class contains words like FOR, AT, WITH, TO, FROM, IN, INTO, IN FRONT OF, BETWEEN, UNDER, BEFORE and quite a few more. But the number of prepositions is still by far less than the number of nouns. What’s more, we don’t create new prepositions, at least not very often. Over long periods of time new prepositions may appear, like for example REGARDING, which derives from a verb, or the preposition ON ACCOUNT OF, which derives from a sequence of orthographic words. However, this does not happen on a regular basis.
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