Tertiary is an adjective that means third in order or level.
Our word of the day comes almost directly from Latin. The word tirtius (TEAR tee oos) means third. Tertiary is most commonly used when listing items. The first of a series would be primary. The second, secondary and the third tertiary.
The weather was the tertiary reason for my relocation to Florida. The first was my new job, and the second was the opportunity to live close to family.