short for "seditious" adjective which the Oxford American Dictionaries defines as:
inciting or causing people to rebel against the authority of a state or monarch : the letter was declared seditious.
ORIGIN late Middle English (in the sense violent strife ): from Old French, or from Latin seditio(n-), from sed- ‘apart’ + itio(n-) ‘going’ (from the verb ire).
A lady at the airport is asked by a security officer: "Do you plan revolution or sedition?"
Answer: Sedition (Obviously, she thought, sedition is not as bas as revolution!)