Dictionary

eccentric

-adjective

1. Not at or in the centre.
2. Not perfectly circular
3. Having a different center.
4. Of a person, deviating from the norm; behaving unexpectedly or differently.
5. (physiology) (of a motion) against or in the opposite direction of contraction of a muscle. (E.g. flexion of the lower arm while flexing the tricep; opening of the jaw while flexing the masseter). (Antonym: concentric)

-noun

1. A disk or wheel with its axis off centre, giving a reciprocating motion.
2. One who does not behave like others.
3. (slang) a kook