| aberrate | To go astray; to diverge. "Their own defective and aberrating vision." (De Quincey) Origin: L. Aberratus, p.pr. Of aberrare; ab + errare to wander. See Err. Source: Websters Dictionary (01 Mar 1998) |
|---|---|
| aberration | 1. <ophthalmology> Any error that results in image degradation. Such errors may be chromatic, spherical, astigmatic chromatic, distortion, or curvature of field: and can result from design or execution, or both. 2. <physics> Failure of an optical or electron-optical lens to produce exact geometrical (and chromatic) correspondence between an object and its image. In a video camera tube or cathode-ray tube, aberrations are when the (electrostatic or electromagnetic) lens does not bring the electron beam to sharply focused points uniformly on the target or screen, or to correct geometrical positions, as the beam is deflected. 3. <zoology> A term which, if used to denote a number of individuals within a species, unequivocally signifies infrasubspecific rank. See: aberration, chromatic, aberration, spherical. (09 Jan 1998) |
| aberration, chromatic | <optics> A defect in a lens or optical system due to the greater refraction of shorter wavelengths over that of loner ones at a lens surface. Hence the focal length of a simple lens is shorter for blue than for red rays. This dispersion of the wave-lengths will cause colour fringes in the image field of a lens with such an aberration. (05 Aug 1998) |
| aberration, spherical | <optics> A lens defect whereby image forming rays of one colour, passing through the outer zones of a lens come to focus at a different distance from the lens than do those of more central rays. With a simple spherical (or plano-spherical) lens the outer rays always meet the axis closer to the lens than do more central rays and the lens is uncorrected or undercorrected. When the reverse is true the lens has been overcorrected. (05 Aug 1998) |
| aberrometer | An instrument for measuring optical aberration or any error in experimentation. Origin: L. Aberratio, aberration, + G. Metron, measure (05 Mar 2000) |
| abetalipoproteinaemia | <biochemistry, disease> A rare congenital disorder that causes the body to not produce chylomicrons, low density lipoprotein (LDL) and very low density lipoprotein (VLDL). Individuals with this condition are unable to properly digest fats. Other findings include ataxia, peripheral neuropathy and other forms of nerve dysfunction. Treatment includes vitamin E. Origin: Gr. Haima = blood (27 Sep 1997) |
| abevacuation | <medicine> A partial evacuation. Source: Websters Dictionary (01 Mar 1998) |
| abeyance | A state of temporary abolition of function. Origin: fr. O. Fr. (05 Mar 2000) |