A major is a field of study that correlates with your interests, hobbies, and passion. A lot of people have interests, hobbies, and passions. These interests, hobbies, and passions make them happy. The major that correlates with their interests, hobbies, and passions will be the one that makes them happy.
A major is a field of study that is easy and convenient for you. Some people want to select a certain major, but that certain major is too hard to study. These people wind up choosing a major that is easier for them. What is the easiest major to study? That is up to you to answer because not all majors are hard and easy for everyone.
A major is a field of study that has an equivalent name to the career that you want to pursue. Some examples are engineering, accounting, nursing, and psychology.
A major is a field of study that is required to get the career that you want to pursue. This definition is similar to the definition where it is a field of study that has an equivalent name to the career that you want to pursue. However, there is a case where this definition comes to play. One case is those who want to be high school teachers. High school teachers have to major in the subject that they want to teach. However, some college students want to pursue another major. Some college students already have a lot of knowledge in their subject area. Some college students think that the major is too hard for them, but teaching it at the high school level is easy. The most common subject where this problem happens is mathematics. Some college students know that they want to teach algebra to students. However, they have to study calculus before they become a high school math teacher. Some school districts have calculus classes while others do not. The mathematics major is there just in case high school math teachers are required to teach calculus.
Which definition of major should you go with? That is up to you to decide.