Picturesque is taken from the Italian word "pittoresco", that means "pertaining to a painter". In the eighteenth century the word referred to the fact that a landscape appeared as if it had just come out of a picture: paintings by Claude and Poussin are excellent examples of this first meaning of picturesque. Now, however, the meaning has changed to mean that a certain scene (whether it is landscape, marketplace, buildings or whatever) is considered a worthwhile subject for an artist to depict in his or her works.
During the eighteenth century, there was quite a controversy over the meaning of picturesque; Jane Austen, the author, satirized picturesque in her book "Sense and Sensibility". Arising out of the controversy was a new definition of beauty, that was composed of a certain roughness, irregularity and some deformity. The Romantic artists of the nineteenth century used these ideas and definitions as a jumping-off place for their own artwork.