, n. (Microbiol.) A group of single-celled microorganisms including the methanogens and some halophiles and thermoacidophiles, recognized in the 1970's by C. R. Woese and his colleagues as being a distinct group on the basis of RNA sequences, cell walls, and coenzymes differing from those of other microbes. It is believed to be an ancient form of living organism that evolved separately from the eubacteria and blue-green algae. It is classified as a separate kingdom by some taxonomists. See also The Archaebacteria. [ PJC ]

n. [ Gr. 'archai^os ancient + -graphy. ] A description of, or a treatise on, antiquity or antiquities. [ 1913 Webster ]

a. [ Gr. 'archai^os ancient + liqiko`s pertaining to a stone. ] (Archæol.) Of or pertaining to the earliest Stone age; -- applied to a prehistoric period preceding the Paleolithic age. [ 1913 Webster ]

n. An archæologist. [ 1913 Webster ]

{ } Relating to archæology, or antiquities; as, archæological researches. -- Ar`*chæ*o*log"ic*al*ly, adv. [1913 Webster]

n. One versed in archæology; an antiquary. Wright. [ 1913 Webster ]

n. [ Gr. 'archaiologi`a; 'archai^os ancient (fr. 'archh` beginning) + lo`gos discourse, le`gein to speak. ] The science or study of antiquities, esp. prehistoric antiquities, such as the remains of buildings or monuments of an early epoch, inscriptions, implements, and other relics, written manuscripts, etc. [ 1913 Webster ]

‖n. [ Gr. 'archai^os ancient + pte`ryx wing. ] (Paleon.) A fossil bird, of the Jurassic period, remarkable for having a long tapering tail of many vertebræ with feathers along each side, and jaws armed with teeth, with other reptilian characteristics. [ 1913 Webster ]

n. 1. an extinct primitive toothed bird with a long feathered tail and three free clawed digits on each wing. [ WordNet 1.5 ]

n. 1. 1 a subclass of primitive reptilelike fossil birds of the Jurassic or early Cretaceous.
Syn. -- subclass Archaeornithes [ WordNet 1.5 ]

a. [ Gr. 'archai^os ancient + sto`ma mouth. ] (Biol.) Applied to a gastrula when the blastopore does not entirely close up. [ 1913 Webster ]

a. [ Gr. 'archai^os ancient + zw^, on animal. ] (Zool.) Like or belonging to the earliest forms of animal life. [ 1913 Webster ]

2. (Geol.) formed in or belonging to the earlier of two divisions of the Precambrian era. archaeozoic life forms
Syn. -- archeozoic [ WordNet 1.5 ]

n. [ Gr. 'archai^os ancient + zw^, on animal. ] the time from 1.5 billion to 5 billion years ago; the time when the earth's crust formed; a time when only unicellular organisms and the earliest forms of life are present.
Syn. -- Archeozoic, Archeozoic era, Archaeozoic era [ WordNet 1.5 ]