Dinner is a word with a few different meanings.
In North America dinner usually means large meal that is eaten in early evening. Sometimes dinner can mean a meal eaten in the middle of the day. This meaning is more common in the Southern United States and the United Kingdom . A more formal definition of "dinner", especially outside North America, is any meal that has several courses. The minimum number of course is often regarded as two but there can be as many as seven. If there is only one course and it is the main meal of the day, then it is called dinner.