aberration

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A deviation from the proper or expected course. See Synonyms at deviation.
2. n. A departure from the normal or typical: events that were aberrations from the norm.
3. n. Psychology A disorder or abnormal alteration in one's mental state.
4. n. A defect of focus, such as blurring in an image.
5. n. An imperfect image caused by a physical defect in an optical element, as in a lens.
6. n. The apparent displacement of the position of a celestial body in the direction of motion of an observer on Earth, caused by the motion of Earth and the finite velocity of light.
7. n. Genetics A deviation in the normal structure or number of chromosomes in an organism.

Century Dictionary and Cyclopedia

1. n. The act of wandering away; deviation; especially, in a figurative sense, the act of wandering from the right way or course; hence, deviation from truth or moral rectitude.
2. n. In pathology: A wandering of the intellect; mental derangement.
3. n. Vicarious hemorrhage.
4. n. Diapedesis of blood-corpuscles.
5. n. Congenital malformation.
6. n. In zoology and botany, deviation from the type; abnormal structure or development.
7. n. In optics, a deviation in the rays of light when unequally refracted by a lens or reflected by a mirror, so that they do not converge and meet in a point or focus, but separate, forming an indistinct image of the object, or an indistinct image with prismatically colored edges. It is called spherical when, as in the former case, the imperfection or blurring arises from the form of curvature of the lens or reflector, and chromatic when, as in the latter case, there is a prismatic coloring of the image arising from the different refrangibility of the rays composing white light, and the consequent fact that the foci for the different colors do not coincide. Thus, in fig. 1, the rays passing through the lens L L near its edge have a focus at A, while those which pass near the axis have a focus at B; hence, an image formed on a screen placed at m m would appear more or less distorted or indistinct.
8. n. In astronomy, the apparent displacement of a heavenly body due to the joint effect of the motion of the rays of light proceeding from it and the motion of the earth. Thus, when the light from a star that is not directly in the line of the earth's motion is made to fall centrally into a telescope, the telescope is in reality inclined slightly away from the true direction of the star toward that in which the earth is moving; just as one running under a vertically falling shower of rain, and holding in his hand a long-necked flask, must incline its mouth forward if he does not wish the sides of the neck to be wetted. This phenomenon, discovered and explained by Bradley (1728), is termed the aberration of light, and its effect in displacing a star is called the aberration of the star. The annual aberration, due to the motion of the earth in its orbit, amounts to 20″.4 in the maximum; the diurnal aberration, due to the rotation of the earth, is only 0″.3 at most. See planetary aberration, below.

GNU Webster's 1913

1. n. The act of wandering; deviation, especially from truth or moral rectitude, from the natural state, or from a type.
2. n. A partial alienation of reason.
3. n. (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.
4. n. (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 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.
5. n. (Physiol.) The passage of blood or other fluid into parts not appropriate for it.
6. n. (Law) The producing of an unintended effect by the glancing of an instrument, as when a shot intended for A glances and strikes B.

WordNet 3.0

1. n. a disorder in one's mental state
2. n. a state or condition markedly different from the norm
3. n. an optical phenomenon resulting from the failure of a lens or mirror to produce a good image