CCC 2353
Life in Christ›SECTION TWO THE TEN COMMANDMENTS›CHAPTER TWO YOU SHALL LOVE YOUR NEIGHBOR AS YOURSELF›II. The Vocation to Chastity
Fornication is carnal union between an unmarried man and an unmarried woman. It is gravely contrary to the dignity of persons and of human sexuality which is naturally ordered to the good of spouses and the generation and education of children. Moreover, it is a grave scandal when there is corruption of the young.