Part of my job is to know the difference between British and American spelling, as well as to root out Britishisms (and sometimes Americanisms, which not so surprisingly I'm rather bad at).
The spelling differences are mostly straightforward - o versus ou, z versus s, er versus re. But however did it happen that the British spell it sceptic and the Americans skeptic? Maybe the Americans were influenced by Swedish: skeptiker is how you say it in Swedish.
- by Francis S.