Tertiary (adjective)

1. Of third rank, importance, or value.
2. Of or relating to education beyond secondary level, typically at college or university.
3. Of or relating to the third period of the Mesozoic Era, between the Cretaceous and Quaternary periods, characterized by the domination of dinosaurs.

Origin:

Late 16th century: from latin tertiarius "third", from ter "three times".

Examples:

1. She received a tertiary degree in engineering.
2. The tertiary sector is the fastest growing part of the economy.
3. The new policy is aimed at reducing emissions from the tertiary sector.
4. The tertiary education system in the country is widely recognized for its quality.
5. The research focused on the recovery of oil and gas in tertiary reservoirs.