It's often used in scientific and academic contexts to refer to something from a very early period, such as:
* Archaeology: The study of ancient people and cultures.
* Archaebacteria: A group of single-celled organisms that are considered to be among the oldest forms of life on Earth.
* Archaean Eon: A geologic eon that lasted from about 4 billion to 2.5 billion years ago.
The prefix "archaios" is the root of many English words, including:
* Archetype: A prototype or original model.
* Archaeology: The study of ancient peoples and cultures.
* Archive: A collection of historical records.