It refers to opposition to the separation of church and state, specifically in relation to the disestablishment of the Church of England in the 19th century.
Here's a breakdown:
* Disestablishment: The act of removing a state-supported church from its privileged position.
* Anti-disestablishment: Opposing the separation of church and state.
* -arianism: A suffix used to indicate a belief or doctrine.
So, "antidisestablishmentarianism" is a belief system that favors a close relationship between the church and the government, as opposed to a separation of powers.
It's important to note that this term is largely historical and is not widely used today.