Archaea
WiktionaryText
Etymology
From , neuter plural of .
Proper noun
- A taxonomic domain of single-celled organisms lacking nuclei, formerly called archaebacteria but now known to differ fundamentally from bacteria.
Usage notes
Whereas in the three-domain system the Archaea comprise a domain, in the short-lived two-empire system they were a kingdom in the domain (or "empire") Prokaryota.