of the third order, rank, stage, formation, etc.; third.

Chemistry .

noting or containing a carbon atom united to three other carbon atoms.

formed by replacement of three atoms or groups.

( initial capital letter ) Geology . noting or pertaining to the period forming the earlier part of the Cenozoic Era, occurring from 65 million to 2 million years ago, characterized by the development and proliferation of mammals.

Ornithology . tertial.

Ecclesiastical . noting or pertaining to a branch, or third order, of certain religious orders that consists of lay members living in community (regular tertiaries) or living in the world (secular tertiaries).

( initial capital letter ) Geology . the Tertiary Period or System.

Ornithology . a tertial feather.

( often initial capital letter ) Ecclesiastical . a member of a tertiary branch of a religious order.

tertiary color.