QUALIFYING ADJECTIVES
248. Qualifying adjectives are also called descriptive adjectives because they describe the noun. They answer the questions which and what kind.
You remember we found in the beginning of our study of English, that words were grouped into classes according to the work which they do in the sentence, not according to the form of the word itself. For instance, we have already found that some words, without changing their form, may be used either as a noun or as a verb. Take the word oil, for instance. I may say, I oil the engine. Here I have used the word oil as a verb telling what I do. But I may say, The oil is gone. Here I have used the word oil as a noun, subject of the sentence. The part of speech to which a word belongs in the English language, always depends upon the work which it does in the sentence.
1. So we have nouns which are used as descriptive adjectives, for example the word oil, which we have found we can use either as a noun or a verb, may also be used as an adjective. For example; I may say, the oil tank. Here I have used the word oil as a descriptive adjective modifying the word tank. So also we may say, the oak tree, the stone curb, the earth wall. In these expressions oak, stone and earth are nouns used as descriptive adjectives.
2. We have descriptive adjectives derived from proper nouns, as French, English, American. These are called proper adjectives; and since all proper nouns must begin with a capital letter, these proper adjectives, also, should always begin with a capital letter.
3. We have also descriptive adjectives derived from verbs as active, talkative, movable, desirable, derived by the addition of suffixes to the verbs act, talk, move and desire.