| arachnephobia | <psychology> Morbid fear of spiders. Synonym: arachnophobia. Origin: G. Arachne, spider, + phobos, fear (05 Mar 2000) |
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| Arachnia | A genus of nonmotile, nonsporeforming, facultatively anaerobic bacteria (family Actinomycetaceae) containing Gram-positive, non-acid-fast, branched, diphtheroid rods (0.2 to 0.3 by 3.0 to 5.0 um and longer). These organisms produce filamentous microcolonies. Their metabolism is fermentative. Primarily propionic and acetic acids are produced from glucose. Catalase is not produced. The cell wall contains diaminopimelic acid but not arabinose. These organisms are pathogenic for man, causing lacrimal canaliculitis and typical actinomycosis. The type species is Arachnia propionica. Arachnia propionica, a species causing lacrimal canaliculitis and typical actinomycosis; it is the type species of the genus Arachnia. Synonym: Propionibacterium propionicus. (05 Mar 2000) |
| arachnid | <biology> An organism of the class Arachnida in the kingdom Animalia. For example: a spider. (09 Oct 1997) |
| arachnid vectors | Members of the class arachnida, especially spiders, scorpions, mites, and ticks, which transmit infective organisms from one host to another or from an inanimate reservoir to an animate host. (12 Dec 1998) |
| arachnida | <zoology> One of the classes of Arthropoda. They have four pairs of legs, no antennae nor wings, a pair of mandibles, and one pair of maxillae or palpi. The head is usually consolidated with the thorax. The respiration is either by trancheae or by pulmonary sacs, or by both. The class includes three principal orders: Araneina, or spiders; Arthrogastra, including scorpions, etc.; and Acarina, or mites and ticks. Origin: NL, fr. Gr. Spider. Source: Websters Dictionary (01 Mar 1998) |
| arachnidan | <zoology> One of the Arachnida. Origin: Gr. Spider. Source: Websters Dictionary (01 Mar 1998) |
| arachnidial | <zoology> Of or pertaining to the Arachnida. Pertaining to the arachnidium. Source: Websters Dictionary (01 Mar 1998) |
| arachnidism | The condition produced by the bite of a venomous spider; spider envenomation. (12 Dec 1998) |
| arachnidium | <zoology> The glandular organ in which the material for the web of spiders is secreted. Origin: NL. See Arachnida. Source: Websters Dictionary (01 Mar 1998) |
| arachnitis | <medicine> Inflammation of the arachnoid membrane. Origin: Gr. +. Source: Websters Dictionary (01 Mar 1998) |
| arachnobutyrophobia | <psychology> Fear of peanut butter. Really !!. Origin: Gr. Phobos = fear (16 Mar 1998) |
| arachnodactyly | <clinical sign> A skeletal disorder where the patient has unusually long, thin bones, especially noticeable in the fingers and toes. (09 Oct 1997) |
| arachnoid | Like a cobweb, covered with or consisting of soft fibres or hairs so entangled as to give a cobwebby appearance. (09 Oct 1997) |
| arachnoid cyst | A fluid-filled cyst lined with arachnoid membrane, frequently situated near the lateral aspect of the fissure of Sylvius; usually congenital in origin. Synonym: leptomeningeal cyst. (05 Mar 2000) |
| arachnoid cysts | Fluid-filled sacs between the layers of the pia mater and arachnoid. These lesions, which often mimic intracranial neoplasms, present clinically at all ages but are probably congenital in origin. (12 Dec 1998) |