| archegonium | <plant biology> The structure on the pteridophyte prothallus that produces the sessile female gametes. Compare: antheridium. (09 Oct 1997) |
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| archegony | <biology> Spontaneous generation; abiogenesis. See: Archegonium. Source: Websters Dictionary (01 Mar 1998) |
| archencephala | <zoology> The division that includes man alone. Origin: NL, fr. Gr. Pref. + the brain. Source: Websters Dictionary (01 Mar 1998) |
| archenteric | <biology> Relating to the archenteron; as, archenteric invagination. Source: Websters Dictionary (01 Mar 1998) |
| archenteric canal | Invagination of the blastopore into the notochordal process to form a cavity. See: neurenteric canal. Synonym: notochordal canal. (05 Mar 2000) |
| archenteron | <biology> The primitive enteron or undifferentiated digestive sac of a gastrula or other embryo. Origin: Pref. Arch- + Gr. Intestine. Source: Websters Dictionary (01 Mar 1998) |
| archeocerebellum | Those regions of the cerebellar cortex whose predominant afferent fibres arise from the ganglion vestibulare and the vestibular nuclei; structures included under this term are nodulus, flocculus, ventral parts of the uvula and small ventral parts of the lingula. Synonym: archeocerebellum. Origin: vestibulo-+ L. Cerebellum (05 Mar 2000) |
| archeokinetic | Denoting a low and primitive type of motor nerve mechanism, such as is found in the peripheral and the ganglionic nervous systems. Compare: neokinetic, paleokinetic. Origin: G. Archaios, ancient, + kinetikos, relating to movement (05 Mar 2000) |
| archeological | Same as Archaeology, etc. Source: Websters Dictionary (01 Mar 1998) |
| archeology | <study> The science or study of antiquities, especially. Prehistoric antiquities, such as the remains of buildings or monuments of an early epoch, inscriptions, implements, and other relics, written manuscripts, etc. Origin: Gr.; ancient (fr. Beginning) + discourse, to speak. (04 Mar 1998) |
| archer fish | <zoology> A small fish (Toxotes jaculator), of the East Indies; so called from its ejecting drops of water from its mouth at its prey. The name is also applied to Chaetodon rostratus. Source: Websters Dictionary (01 Mar 1998) |
| archeress | A female archer. Source: Websters Dictionary (01 Mar 1998) |
| arches of the foot | See: longitudinal arch of foot, plantar arch. (05 Mar 2000) |
| archetype | 1. The original pattern or model of a work; or the model from which a thing is made or formed. "The House of Commons, the archetype of all the representative assemblies which now meet." (Macaulay) "Types and shadows of that glorious archetype that was to come into the world." (South) 2. The standard weight or coin by which others are adjusted. 3. <biology> The plan or fundamental structure on which a natural group of animals or plants or their systems of organs are assumed to have been constructed; as, the vertebrate archetype. Origin: L. Archetypum, Gr, fr. Stamped first and as model; + stamp, figure, pattern, to strike: cf. F. Archetype. See Arch-, pref. Source: Websters Dictionary (01 Mar 1998) |
| archeus | Term first used by Valentine and later by Paracelsus and van Helmont to denote a spirit that presided over and governed bodily processes. Synonym: archeus. Origin: L. Fr. G. Archaios, chief, leader (05 Mar 2000) |