* Carrera: This is the most common and generally accepted translation. It refers to a professional career or course of study. "Mi carrera es ingeniería" (My major is engineering).
* Especialidad: This word means "specialty" and is suitable when you want to emphasize the specific area of study within a broader field. "Mi especialidad es bioquímica" (My specialty is biochemistry).
* Licenciatura (in some countries): In some Spanish-speaking countries, particularly in Latin America, "licenciatura" refers to a bachelor's degree. You could say "Mi licenciatura es en literatura" (My bachelor's degree is in literature), but this emphasizes the degree rather than the major itself. In other countries, a "licenciatura" might be a different type of degree.
* Major (loanword): The English word "major" is often used directly in Spanish, particularly in informal settings or when speaking to someone who understands English.
In summary: For most situations, carrera is the best option. Use especialidad if you want to highlight a specific area within a larger field. Consider licenciatura only if the context focuses on the degree itself, and be aware of regional variations. Using "major" is acceptable in informal contexts.