Opposition to separation of the church and state.
[From Latin anti- (against) + dis- (apart, away) + English establish, from
Latin stabilire, from stare (to stand) + -arian (one who supports) + Greek
-ism (practice or state).]
At 28 letters, it's the best-known example of a long word. Here's how you
can parse the word: one of the meanings of the word establishment is making
a church an institution of the state. In the late 19th century England, there
was a movement for the separation of the church and state: disestablishment.
Those opposed to the idea of separation were antidisestablishmentarians.
You can see where it's going. Why not a contraantidisestablishmentarianism?
-Anu Garg (gargATwordsmith.org)
"As we said yesterday, the case for antidisestablishmentarianism has never
been more threadbare. And if the case for the sovereign as head of a
meaningful faith has gone, then the case for the sovereign has changed
Royal Wedding: Crowning Nonsense; The Guardian (London, UK); Apr 9, 2005.
Update: LOL! I stand hereby throughly corrected Via Bruce in the Comments section.
Furthermore, I find myself a bit dissapointed by your meager “wordsmith.org” reference; surely you meant to refer to the more lengthy wikipedia explanation, http://en.wikipedia.org/wiki/Antidisestablishmentarianism