Definitions

1. adjective

belonging to the third in a series of three; of the third level or stage in a series of three

“The tertiary education system provides advanced degrees for students.”

2. noun

a third-level education, especially a university or college

“She attended a tertiary institution in the city.”

3. noun

a third-level structure or part, especially in the mouth, consisting of molars and premolars

“The dentist examined her tertiary teeth for cavities.”

4. noun

a third-level division or classification

“The company’s tertiary division focuses on marketing and advertising.”