Literally the behaviour expected in a
city - from the
latin cives. Generally taken to mean conforming with the standards of the society in which the person using the word lives.
No more a misspelling than
colour or
sulphur - rather the way every
Anglophone outside the
USA spells it.
See also
politeness,
culture.
The misspelling part of this w/u was in response to a now-nuked w/u saying this was a misspelling of civilized.