Comparative adjectives are words that describe nouns, but they also compare two nouns. Usually the comparative adjective contains "er" at the end of the word. If the adjective is a longer word, then the writer needs to put the word "more" in front of the adjective in order to compare. For example, bigger is a comparative adjective. It may be comparing one thing that is bigger than the other thing. Also, the comparative adjective "more helpful" is another. However, one would not put "er" onto the end of the word "helpful." This is because there is no such word as "helperfuler."