| aphanite | <chemical> A very compact, dark-coloured ock, consisting of hornblende, or pyroxene, and feldspar, but neither of them in perceptible grains. Origin: Gr. Invisible; priv. + to appear. Source: Websters Dictionary (01 Mar 1998) |
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| aphanitic | <chemical> Resembling aphanite; having a very fine-grained structure. Source: Websters Dictionary (01 Mar 1998) |
| aphasia | <clinical sign, neurology> A defect or loss of the ability to speak or write, loss of ability to understand spoken or written language, due to injury or disease of the brain centres. Origin: Gr. Phasis = speech (16 Dec 1997) |
| aphasia, broca | Loss of ability to speak and write caused by damage to the motor association cortex in the frontal lobe (broca's area). The deficit in language production ranges from almost complete muteness to a slowed, deliberate speech constructed from very simple grammatical structures. Patients use only key words: for "the large gray cat" the patient with broca's aphasia may say "gray cat". (kandel et al., principles of neural science, 3d ed, p847) (12 Dec 1998) |
| aphasia, conduction | A type of fluent aphasia in which there is normal comprehension of spoken language but words are repeated incorrectly. It results from a lesion of the arcuate fasciculus connecting broca's and wernicke's areas. Like patients with wernicke's aphasia (aphasia, wernicke), patients with conduction aphasia are fluent but have many paraphasic errors (incorrect words or sounds substituted for correct ones). The degree of fluency is less than that in wernicke's aphasia, but comprehension is good. (12 Dec 1998) |
| aphasia, primary progressive | A type of aphasia appearing gradually and gradually worsening without any major change in other cognitive functions. It is regarded by some authors as a syndrome which may be due to various degenerative diseases of the cerebral cortex (notably alzheimer disease, owing to its frequency), while others see in it an autonomous disease related to a neuropathological process that is distinct from the main degenerative dementias. The principal clinical peculiarity of primary progressive aphasia is that it spares the patient's autonomy for a long time, but ultimately turns into global dementia. (12 Dec 1998) |
| aphasia, wernicke | Impairment in the comprehension of speech and meaning by words, both spoken and written, and of the meanings conveyed by their grammatical relationship in sentences. It is caused by a lesion primarily affecting wernicke's area, the left posterior portion of the temporal lobe. (12 Dec 1998) |
| aphasic | Relating to or suffering from aphasia. (05 Mar 2000) |
| aphasiologist | A specialist who deals with speech disorders caused by dysfunction of the language areas of the brain. (05 Mar 2000) |
| aphasiology | The science of speech disorders caused by dysfunction of the cerebral language areas. (05 Mar 2000) |
| aphasmid | 1. Lacking phasmids, as seen in nematodes of the class Adenophorasida (Aphasmidia). 2. Common name for a member of the class Aphasmidia, now Adenophorasida. (05 Mar 2000) |
| Aphasmidia | A class of nematodes lacking lateral canals opening into the excretory system and phasmids, with few or no caudal papillae, eggs unsegmented, and with polar plugs or hatching in utero. It includes the genera Trichuris, Capillaria, and Trichinella among important parasites of man and domestic animals. See: Secernentasida. Synonym: Adenophorea, Aphasmidia. Origin: G. Aden, gland, + phor, thief (05 Mar 2000) |
| aphasy | <medicine> Loss of the power of speech, or of the appropriate use of words, the vocal organs remaining intact, and the intelligence being preserved. It is dependent on injury or disease of the brain. Origin: NL. Aphasia, Gr, fr. Not spoken; priv. + to speak: cf. F. Aphasie. Source: Websters Dictionary (01 Mar 1998) |
| aphelion | <astronomy> That point of a planet's or comet's orbit which is most distant from the sun, the opposite point being the perihelion. Source: Websters Dictionary (01 Mar 1998) |
| apheliotropism | The habit of bending from the sunlight; said of certain plants. Source: Websters Dictionary (01 Mar 1998) |