Your friend Robert drives a fast car. The word "fast" is? a preposition, adverb, adjective

When they reached the door of the lonely house and stopped to unlock it, and the cat came to purr loudly, and rub against them, a deserted p***y, indeed, but fat with young robins, sylvia whispered that this was a beautiful place to live in, and she never should wish to go home. the description of the house in this excerpt gives an example of