Definition

1. Adjective:

   • Coming next after the second and just before the fourth in position: "Tertiary" describes something that is third in a sequence, order, or level of importance.
   • Relating to or characteristic of a third stage or level: Often used to describe a third level of education, a third stage in a process, or a third level of structure.

2. Noun (Proper Noun, often capitalized):

   • The Tertiary period: In geology, the Tertiary is the former name for a major period of geological time, from about 66 million to 2.6 million years ago, now often subdivided into the Paleogene and Neogene periods. It followed the Cretaceous period and preceded the Quaternary period.

Usage Examples

• Adjective:
  • Primary education is followed by secondary, and then tertiary education.
  • After the primary and secondary stages of review, the proposal entered its tertiary phase.
• Noun:
  • Many modern mammals evolved during the Tertiary.
  • Fossils from the Tertiary show a diversification of flowering plants.

Advanced Usage

• Tertiary sector: In economics, the sector of the economy concerned with services, as distinct from the primary (raw materials) and secondary (manufacturing) sectors.
  • Tourism is a major part of the tertiary sector in many countries.
• Tertiary color: A color made by mixing two secondary colors, or a primary with a secondary color.
  • Olive green is a tertiary color.
• Tertiary source: In research, a source that compiles and summarizes information from primary and secondary sources, such as encyclopedias.
  • A textbook is often considered a tertiary source.

Variants and Related Words

• Tertiarity (n, rare): The state or quality of being tertiary.
• Tertiarily (adv): In a tertiary manner; thirdly.

Synonyms

• Third: The ordinal number corresponding to three.
• Triennial (adj): Lasting for or recurring every three years (note: this is a specific type of third).

Antonyms

• Primary: First in order or importance.
• Secondary: Coming after, or less important than, something primary.

Related Phrases/Idioms

• Tertiary education: Education at the college or university level, following secondary school.
  • Access to tertiary education has increased in recent decades.
• Tertiary treatment: In wastewater management, an advanced cleaning process that follows primary and secondary treatment.
  • The new plant includes tertiary treatment to remove nitrates.

Adjective

1. coming next after the second and just before the fourth in position

Noun

1. from 63 million to 2 million years ago