The signification of the noun is limited to one, but to any one of the kind, by the indefinite article, and to some particular one, or some particular number, by the definite article.
Nouns, in one form, represent one of a kind, and in another, any number more than one; they are the names of males, or females, or of objects which are neither male nor female; and they represent the subject of an affirmation, a command or a question,—the owner or possessor of a thing,—or the object of an action, or of a relation expressed by a preposition.
Adjectives express the qualities which distinguish one person or thing from another; in one form they express quality without comparison; in another, they express comparison between two, or between one and a number taken collectively,—and in a third they express comparison between one and a number of others taken separately.
Pronouns are used in place of nouns; one class of them is used merely as the substitutes of names; the pronouns of another class have a peculiar reference to some preceding words in the sentence, of which they are the substitutes,—and those of a third class refer adjectively to the persons or things they represent. Some pronouns are used for both the name and the substitute; and several are frequently employed in asking questions.
Affirmations and commands are expressed by the verb; and different inflections of the verb express number, person, time and manner. With regard to time, an affirmation may be present or past or future; with regard to manner, an affirmation may be positive or conditional, it being doubtful whether the condition is fulfilled or not, or it being implied that it is not fulfilled;—the verb may express command or entreaty; or the sense of the verb may be expressed without affirming or commanding. The verb also expresses that an action or state is or was going on, by a form which is also used sometimes as a noun, and sometimes to qualify nouns.
Affirmations are modified by adverbs, some of which can be inflected to express different degrees of modification.
Words are joined together by conjunctions; and the various relations which one thing bears to another are expressed by 'prepositions. Sudden emotions of the mind, and exclamations are expressed by interjections.
Some words according to meaning belong sometimes to one part of speech, sometimes to another. Thus, in "After a storm comes a calm," calm is a noun; in "It is a calm evening," calm is an adjective; and in "Calm your fears," calm is a verb.
The following sentence containing all the parts of speech is parsed etymologically:
"I now see the old man coming, but, alas, he has walked with much difficulty."