The problem of parts of speech is a controversial one both in general linguistic theory and in the particular case of many languages. The very term parts of speech implying the idea of something divided into different smaller parts seems to oversimplify the rather complex relationships which, by necessity, link the same parts of speech to form meaningful utterances. What is usually meant by a part of speech is a type of word differing from other types in some grammatical point or points of view. For example, the verb is a type of word differing from all other types in that it alone has the grammatical category of tense. Thus, one can reasonably ask "what is the past tense of the word like (that is liked) but it Would seem stupid to ask "what is the past tense of the word interesting" or "what is the past tense of the word like. These words do not have any past, present or future tense since the notion of tense cannot be applied to them. Tense is one of the grammatical distinctive features characterizing the verb as against every other type of word. However, the question is much less'simple with reference to some other types of words such as adjectives turned noun's or nouns turned verbs by conversion or verbal nouns for that matter and this is why we will consider a general definition of the principles on Which the classification of the English parts of speech should be based in order to facilitate their recognition as individual entities.
 

The principles on which such a classificatioh can be made are three in number: meaning - form - function
 

By meaning we do not mean the individual meaning of each separate word (its lexical meaning) but the meaning common to all the words of the given class and constituting its essence. Thus, the meaning of the noun is thingness (implying everything that is presented as a thing, or object such as gold, beauty, book, etc.). It is to be noted that while the criterion of meaning can be very easily applied to denominate a noun, an adjective (which is said to express property or characteristic) or a verb (said to express a process), things get more complicated when it comes to articles, pronouns or adverbs.