Open And Closed Word Classes

Open and Closed Word Classes
Some word classes are OPEN, that is, new words can be added to the class as the need arises. The class of nouns, for instance, is potentially infinite, since it is continually being expanded as new scientific discoveries are made, new products are developed, and new ideas are explored. In the late twentieth century, for example, developments in computer technologyhave given rise to many new nouns:
Internet, website, URL, CD-ROM, email, newsgroup, bitmap, modem, multimedia
New verbs have also been introduced:
download, upload, reboot, right-click, double-click
The adjective and adverb classes can also be expanded by the addition of new words, though less prolifically. 
On the other hand, we never invent new prepositions, determiners, orconjunctions. These classes include words like of, the, and but. They are called CLOSED word classes because they are made up of finite sets of words which are never expanded (though their members may change their spelling, for example, over long periods of time). The subclass of pronouns, within the open noun class, is also closed. 
Words in an open class are known as open-class items. Words in a closedclass are known as closed-class items.  
In the pages which follow, we will look in detail at each of the seven major word classes. 
  Open and Closed Word Classes
In linguistics, a word class may be either an open class or a closed class. Open classes accept the addition of new morphemes (words), through such processes as compounding, derivation, inflection, coining, and borrowing; closedclasses generally do not.
Content words, or lexical words (including nouns, verbs, adjectives, and most adverbs), are words that carry the content or the meaning of a sentence, are open-class words. They contrast with function (or grammatical, or closed-class) words, such as articles, prepositions, conjunctions, auxiliary verbs, and pronouns, which can be found in almost any utterance, no matterwhat it is about. Words in open classes (content and lexical words)) carry the primary communicative force of an utterance, and are variable in form (inflected), and their distribution is not definable by the grammar.
Typical open classes are the class of nouns, the class of verbs, the class of adjectives,[1] and the class of adverbs.[2] However, this varies between languages; for example, inJapanese, pronouns form an open class, while verbs form a closed class: with a few exceptions, such as サボる (saboru, "to ditch class") and ぐぐる (guguru, "to google"), new "verbs" are formed by appending する (suru, "to do") to a noun.
Open-class words are not considered part of the core language[citation needed] and as such they can be changed, replaced or dropped from the common lexicon, which canencompass many thousands of them. For living languages, this change is noticeable within an individual lifespan, and usually faster. Closed-class words, on the other hand, are always relatively few and resistant to change. They are unproductively and are generally invariable in form (except demonstratives, modals and some pronouns).
English Open Word Classes
In English, open classes include thefollowing parts of speech:
* Nouns
* Main verbs (not auxiliary verbs)
* Adjectives
* Adverbs
* Interjections
closed- and open-class items (function words, grammar words)
• All English words can be classified as belonging to a “closed class” or an “open class.” (Closed-class words are also called “function words” or “grammar words” and open-class words are also called “lexicalwords” or “content words.” Closed classes are called “closed” because new words are seldom added to them. By contrast, new items are regularly added to the open classes. The entire noun word class is made up of closed-class items as is the entire sub-class of full verbs. All determiners, pronouns, conjunctions, prepositions are closed class. The adverb word class is partly open and partly closed.)...