diurnal aberration

Aberration Ab`er*ra"tion, n. [L. aberratio: cf. F. aberration. See {Aberrate}.] 1. The act of wandering; deviation, especially from truth or moral rectitude, from the natural state, or from a type. ``The aberration of youth.'' --Hall. ``Aberrations from theory.'' --Burke. [1913 Webster]

2. A partial alienation of reason. ``Occasional aberrations of intellect.'' --Lingard. [1913 Webster]

Whims, which at first are the aberrations of a single brain, pass with heat into epidemic form. --I. Taylor. [1913 Webster]

3. (Astron.) A small periodical change of position in the stars and other heavenly bodies, due to the combined effect of the motion of light and the motion of the observer; called {annual aberration}, when the observer's motion is that of the earth in its orbit, and daily or {diurnal aberration}, when of the earth on its axis; amounting when greatest, in the former case, to 20.4'', and in the latter, to 0.3''. {Planetary aberration} is that due to the motion of light and the motion of the planet relative to the earth. [1913 Webster]

4. (Opt.) The convergence to different foci, by a lens or mirror, of rays of light emanating from one and the same point, or the deviation of such rays from a single focus; called {spherical aberration}, when due to the spherical form of the lens or mirror, such form giving different foci for central and marginal rays; and {chromatic aberration}, when due to different refrangibilities of the colored rays of the spectrum, those of each color having a distinct focus. [1913 Webster]

5. (Physiol.) The passage of blood or other fluid into parts not appropriate for it. [1913 Webster]

6. (Law) The producing of an unintended effect by the glancing of an instrument, as when a shot intended for A glances and strikes B. [1913 Webster]

Syn: Insanity; lunacy; madness; derangement; alienation; mania; dementia; hallucination; illusion; delusion. See {Insanity}. [1913 Webster]