1. A domain of single-celled microorganisms that are prokaryotes, often found in extreme environments such as hot springs, salt lakes, and deep-sea vents.
Usage: plural of archaeon; scientific/technical term; also called archaebacteria (older term, less common)

Examples

• Archaea are distinct from bacteria and eukaryotes, forming a separate domain of life.
• Scientists discovered archaea thriving in boiling hot springs where most other organisms cannot survive.
• Some archaea produce methane and are used in wastewater treatment facilities.
• The study of archaea has revealed how life can exist in extreme conditions.
• Archaea were originally thought to be bacteria until genetic analysis showed they were fundamentally different.
• Certain archaea live in salt-saturated environments that would be lethal to most other microorganisms.