elective
[ˈɛlɛktɪv]
Definitions
1. noun
a course or subject in a school or college that a student can choose to study, especially in the final years of secondary or higher education
“She chose to take an elective in psychology to broaden her knowledge.”
2. adjective
chosen or selected freely, especially from a range of alternatives
“The company offered elective payment plans to its customers.”
3. adjective
related to or used in the practice of choosing one option from several
“The elective system allowed students to pick their own courses.”