eccentric

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Departing from a recognized, conventional, or established norm or pattern. synonym: strange.
• adjective Deviating from a circular form or path, as in an elliptical orbit.
• adjective Not having the same center.
• adjective Having the axis located elsewhere than at the geometric center.
• noun One that deviates markedly from an established norm, especially a person of odd or unconventional behavior.
• noun Physics A disk or wheel having its axis of revolution displaced from its center so that it is capable of imparting reciprocating motion.

from The Century Dictionary.

• In astronomy, noting orbital motion which is not in a circle around the center of attraction; as applied to curves generally, deviating from circularity, as the ellipse and hyperbola.
• Not located or situated in the center; away from the center or axis: as, in botany, lateral embryos and the stipes of some hymenomycetous fungi are said to be eccentric.
• In medicine, not originating or existing in the center or central parts; due to peripheral causes: as, eccentric irritation; eccentric convulsions (that is, convulsions due to peripheral irritation).
• Not coincident as regards center; specifically, in geometry, not having the same center: applied to circles and spheres which have not the same center, and consequently are not parallel: opposed to concentric, having a common center.
• Not coincident as regards course or aim; tending to a different end or result; devious.
• Deviating, or characterized by deviation, from recognized, stated, or usual methods or practice, or from established forms, laws, etc.; irregular; erratic; odd: as, eccentric conduct; an eccentric person.
• Of or pertaining to an eccentric: as, the eccentric anomaly of a planet; the eccentric rod of a steam-engine.
• In senses 3 and 6 sometimes written excentric.
• noun In ancient astronomy, a circle having its center remote from the earth and carrying an epicycle which in its turn was supposed to carry a planet.
• noun In mod. astron., a circle described about the center of an elliptical orbit, with half the major axis for radius.
• noun In mech., a device for converting a regular circular motion into an irregular reciprocating rectilinear motion.
• noun One who or that which is irregular or anomalous in action; a person of eccentric habits.

from the GNU version of the Collaborative International Dictionary of English.

• noun A circle not having the same center as another contained in some measure within the first.
• noun One who, or that which, deviates from regularity; an anomalous or irregular person or thing.
• noun In the Ptolemaic system, the supposed circular orbit of a planet about the earth, but with the earth not in its center.
• noun A circle described about the center of an elliptical orbit, with half the major axis for radius.
• noun (Mach.) A disk or wheel so arranged upon a shaft that the center of the wheel and that of the shaft do not coincide. It is used for operating valves in steam engines, and for other purposes. The motion derived is precisely that of a crank having the same throw.
• noun the eccentric that reverses or backs the valve gear and the engine.
• noun the eccentric that imparts a forward motion to the valve gear and the engine.
• adjective Deviating or departing from the center, or from the line of a circle; ; pertaining to deviation from the center or from true circular motion.
• adjective Not having the same center; -- said of circles, ellipses, spheres, etc., which, though coinciding, either in whole or in part, as to area or volume, have not the same center; -- opposed to concentric.
• adjective (Mach.) Pertaining to an eccentric.
• adjective Not coincident as to motive or end.
• adjective Deviating from stated methods, usual practice, or established forms or laws; deviating from an appointed sphere or way; departing from the usual course; irregular; anomalous; odd.
• adjective (Astron.) See Anomaly.
• adjective (Mach.) a lathe chuck so constructed that the work held by it may be altered as to its center of motion, so as to produce combinations of eccentric combinations of eccentric circles.
• adjective (Mach.) A cogwheel set to turn about an eccentric axis used to give variable rotation.
• adjective a hook-shaped journal box on the end of an eccentric rod, opposite the strap.
• adjective the rod that connects an eccentric strap with any part to be acted upon by the eccentric.
• adjective an eccentric.
• adjective the ring, operating as a journal box, that encircles and receives motion from an eccentric; -- called also eccentric hoop.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective not at or in the centre.
• adjective not perfectly circular.
• adjective having a different center.
• adjective of a person deviating from the norm; behaving unexpectedly or differently.
• adjective physiology (of a motion) against or in the opposite direction of contraction of a muscle. (E.g. flexion of the lower arm (bending of the elbow joint) by an external force while contracting the triceps and other elbow extensor muscles to control that movement; opening of the jaw while flexing the masseter).
• noun One who does not behave like others.
• noun A disk or wheel with its axis off centre, giving a reciprocating motion.
• noun slang A kook.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a person of a specified kind (usually with many eccentricities)