Origin: Latin suffix -ary
Tertiary has 6 different meanings across 3 categories:
Noun · Adjective · Proper Noun
from 63 million to 2 million years ago
"Geologists study rock formations that date back to the tertiary period, spanning from 63 million to 2 million years ago."
Any item considered to be of third order.
"The tertiary sector includes services like banking and education, which support the production industries."
In plain English: A tertiary is someone who comes third in line, such as an understudy waiting for their turn after two others have already performed.
"The tertiary sector includes all service industries like retail and tourism that support primary production."
Of third rank or order; subsequent.
"The tertiary fossils found in that rock layer reveal the early appearance of modern mammals during the first period of the Cenozoic era."
Of or pertaining to the first part of the Cenozoic era when modern flora and mammals appeared.
In plain English: Tertiary means being third in order, rank, or importance after two other things have come before it.
"The teacher explained that tertiary education comes after you finish high school."
Usage: Use "tertiary" specifically for the third level in a hierarchy, such as education levels or geological eras, rather than as a general synonym for "third." Avoid using it to describe items that are merely less important unless they explicitly belong to a defined three-tier system.
The first part of the Cenozoic era when modern flora and mammals appeared.
"Geologists divide the Cenozoic era into periods, beginning with the Tertiary when modern flora and mammals first emerged."
The word tertiary comes from Latin tertius, meaning "third," which itself traces back to a common ancient root shared with the English word third. It entered Middle English as an adjective describing things related to the third part or rank of something.