A main course is the featured or primary dish in a meal consisting of several courses. It usually follows the entrée ("entry") course and the salad course. In North American usage it may, in fact, be called the "entrée".
The main course is usually the heaviest, heartiest, and most complex or substantive dish on a menu. The main ingredient is usually meat or fish; in vegetarian meals, the main course sometimes attempts to mimic a meat course. It is most often preceded by an appetizer, soup, and/or salad, and followed by a dessert. For those reasons the main course is sometimes referred to as the "meat course".
In formal dining, a well-planned main course can function as a sort of gastronomic apex or climax. In such a scheme, the preceding courses are designed to prepare for and lead up to the main course in such a way that the main course is anticipated and, when the scheme is successful, increased in its ability to satisfy and delight the diner. The courses following the main course then calm the palate and the stomach, acting as a sort of dénouement or anticlimax.