Definition of tertiary in English:

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Pronunciation: /ˈtəːʃ(ə)ri/


1Third in order or level: the tertiary stage of the disease
More example sentences
  • Yet the poor still resort to the public services for more of their secondary and tertiary level care than do the better off.
  • There is a strong echo of elegance, but the tertiary flavours of nut and oxidised or Madeira-like notes are now coming to the foreground.
  • The Mediterranean theater has long been a theater of tertiary importance to the legion of historians writing about World War II.
1.1chiefly British Relating to or denoting education at a level beyond that provided by schools, especially that provided by a college or university.
Example sentences
  • In response to the need to improve access to tertiary education, universities are increasingly implementing online delivery solutions.
  • Physicians and some nurses are educated at universities, and tertiary education is expensive.
  • The scholarship also involves tertiary study through the University of Queensland.
1.2Relating to or denoting the medical treatment provided at a specialist institution: patients in tertiary care
More example sentences
  • A dermatologist from an academic tertiary care medical center agreed to serve as an expert consultant.
  • He continued to have moderate angina and was referred to a tertiary care medical center for evaluation.
  • During 1990-2000, 194 new patients were referred to a specialist tertiary centre for the treatment and management of venous leg ulcers.
2 (Tertiary) Geology Relating to or denoting the first period of the Cenozoic era, between the Cretaceous and Quaternary periods, and comprising the Palaeogene and Neogene sub-periods.
Example sentences
  • The annihilation of the dinosaurs marks the boundary linking Cretaceous time and Tertiary time.
  • In contrast to parts of the External Hellenides, the Menderes nappes do not show Tertiary high-pressure metamorphism.
  • A cover of undeformed Middle-Upper Miocene to Pliocene rocks is present in all the Tertiary basins.
3 Chemistry (Of an organic compound) having its functional group located on a carbon atom which is itself bonded to three other carbon atoms.
Example sentences
  • If the hydroxyl group is bound to a carbon atom that is itself bound to three other carbon atoms then the resultant alcohol is a tertiary alcohol.
  • The reaction of Grignard reagents with carbonyl compounds is used to prepare primary, secondary, and tertiary alcohols.
  • Esters can be used to manufacture tertiary alcohols by using a Grignard reagent.
3.1(Chiefly of amines) derived from ammonia by replacement of three hydrogen atoms by organic groups.
Example sentences
  • This photoreaction is highly dependent on the amine structure and is efficient only in the presence of tertiary aliphatic amines.
  • This enzyme system catalyses the oxidative deamination of primary aromatic amines, long-chain diamines and tertiary cyclic amines.
  • One or more of the hydrogens of the ammonia is replaced with an organic acid group to produce a primary, secondary, or tertiary amide.


1 (the Tertiary) Geology The Tertiary period or the system of rocks deposited during it.

The Tertiary lasted from about 65 to 1.6 million years ago. The mammals diversified following the demise of the dinosaurs and became dominant, as did the flowering plants.

2A lay associate of certain Christian monastic organizations: a Franciscan tertiary
More example sentences
  • Though contemporary treatises recommended that widows and Franciscan tertiaries be discreetly covered, there is evidence that in their demeanor and in their dress younger widows were perceived as presenting a seductive appeal to men.
  • If we take St Francis of Assisi as the likely subject, however, a direct relationship emerges with St Elizabeth of Hungary and her great-niece St Elizabeth of Portugal, both of whom were Franciscan tertiaries.
  • The beguines and tertiaries, and to some extent the newer Cistercian nuns, were drawn from rising social strata - new groups that may have been anxious about their wealth and status.


Mid 16th century (in sense 2 of the noun): from Latin tertiarius 'of the third part or rank', from tertius 'third'.

For editors and proofreaders

Line breaks: ter|tiary

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