Out of the center...

From Medieval Latin eccentricus, derived from Greek ekkentros, from ek-, ex- "out of" + kentron "center". Eccentric first appeared in English in 1551 as an astronomical term meaning "a circle in which the earth, sun. etc. deviates from its center." Five years later, in 1556, an adjective form of the word was added. 129 years later, in 1685, the definition evolved from the literal to the figurative, and eccentric began being used to describe unconventional or odd behavior. A noun form of the word – a person who possesses and exhibits these unconventional or odd qualities/behaviors – didn't appear until 1832.

(via Wikipedia)