1. A single-celled microorganism belonging to the domain Archaea, characterized by a lack of a membrane-bound nucleus and distinct from bacteria and eukaryotes.
Usage: scientific; biology; plural: archaea

Examples

• Archaeons thrive in extreme environments such as hot springs and salt lakes.
• Scientists discovered that archaeons are genetically distinct from bacteria.
• Many archaeons are methane-producing organisms found in swamps and digestive systems.
• The study of archaeons has revealed new branches of the tree of life.
• Archaeons can survive in conditions that would kill most other microorganisms.