eccentric

Etymology

From Middle French excentrique, from Medieval Latin eccentricus, from Ancient Greek ἔκκεντρος (ékkentros, “not having the earth as the center of an orbit”), from ἐκ (ek, “out”) + κέντρον (kéntron, “point”). Equivalent to ex- + -centric.

adj

1. Not at or in the centre; away from the centre.
   Strikingly, we see that party births tend systematically to be at policy positions that are significantly more eccentric than those of surviving parties, whatever decision rule these parties use. 2011, Michael Laver, Ernest Sergenti., Party Competition: An Agent-Based Model, page 125
2. Not perfectly circular; elliptical.
   As of 2008, Margaret had the most eccentric orbit of any moon in the solar system, though Nereid's mean eccentricity is greater.
3. Having a different center; not concentric.
4. (of a person) Deviating from the norm; behaving unexpectedly or differently; unconventional and slightly strange.
   1801, Author not named, Fyfield (John), entry in Eccentric Biography; Or, Sketches of Remarkable Characters, Ancient and Modern, page 127, He was a man of a most eccentric turn of mind, and great singularity of conduct.
   Such is not the case with Mr. Martin Van Butchell, one of the most eccentric characters to be found in the British metropolis, and a gentleman of indisputable science and abilities, but whose strange humors and extraordinary habits, have rather tended to obscure than to display the talents he possessed. 1807, G. H. Wilson, editor, The Eccentric Mirror, volume 3, page 17
   There can be no doubt that as a matter of fact a religious life, exclusively pursued, does tend to make the person exceptional and eccentric. 1902, William James, The Varieties of Religious Experience, Lecture I
   Khedron was the only other person in the city who could be called eccentric—and even his eccentricity had been planned by the designers of Diaspar. 1956, Arthur C. Clarke, The City and the Stars, published 2012, unnumbered page
5. (physiology, of a motion) Against or in the opposite direction of contraction of a muscle (such as results from 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).
6. Having different goals or motives.
   a. 1626, Francis Bacon, 1867, Richard Whately (analysis and notes), James R. Boyd (editor), Essay XI: Wisdom for a Man's Self, Lord Bacon's Essays, page 171, […] for whatsoever affairs pass such a man's hands he crooketh them to his own ends, which must needs be often eccentric to those of his master or state: […]

noun

1. One who does not behave like others.
   A tiny, feisty woman who always spoke her mind, Charlotte was an eccentric in the wonderful way that some women from the last century were natural eccentrics. 1989, Jeffrey Robinson, Rainier and Grace, page 26
   Eccentrics live longer, happier, and healthier lives than conformist normal citizens, according to the neuropsychologist David Weeks. 1998, Michael Gross, Life On The Edge, published 2001, page ix
2. (slang) A kook; a person of bizarre habits or beliefs.
3. (geometry) A circle not having the same centre as another.
4. (engineering) A disk or wheel with its axis off centre, giving a reciprocating motion.
   The position of the eccentrics which is necessary to make the pistons drive the engine forward must be directly the reverse of that which would cause them to drive the engine backwards. To be able, therefore, to reverse the motion of the engine, it would only be necessary to be able to reverse the position of the eccentrics, which may be accomplished by either of two expedients. 1840, Dionysius Lardner, The Steam Engine Explained and Illustrated, page 379
   Clavius goes on to use the large number of orbs in Fracostoro's theory as another reason to prefer the Ptolemaic system, then couples this issue with that of the relative capacity of the theories to save the phenomena, then finally reiterates the lack (as he sees it) of conflict between the Aristotelian natural philosophy and the eccentrics and epicycles of mathematical astronomy. 1994, James M. Lattis, Between Copernicus and Galileo: Christoph Clavius and the Collapse of Ptolemaic Cosmology, page 116
   The discussion that revolved around the admissibility of eccentrics and epicycles lied at the core of this theoretical discussion, and those who would not allow such concepts took the position that such eccentrics and epicycles would then introduce a center of heaviness, other than the Earth, around which celestial simple objects would then move. 2007, George Saliba, Islamic Science and the Making of the European Renaissance, page 120
5. (physiology) An exercise that goes against or in the opposite direction of contraction of a muscle.
   Research tells us that eccentrics, heavy partials, and static exercise may require several days or weeks of recovery time. 2021, Edward L. Wallace, Omniflex: A Unified System of Strength Training