How many adjectives are there in the English language?

A quarter of the English words are adjectives

It is impossible to provide an exact response to this question.  The main idea is that it is difficult to count the number of words in a language, because it is complicated to decide what actually counts as a word.  Anyway, a quarter of the English words are adjectives.  When it comes to the English language, you should know that over half of these words are nouns, about a quarter adjectives, and about a seventh are verbs.  Needless to say, the rest is made up of exclamations, conjunctions, prepositions, suffixes.