The Collaborative International Dictionary of English v.0.48:

Sedition \Se*di"tion\, n. [OE. sedicioun, OF. sedition, F.
   s['e]dition, fr. L. seditio, originally, a going aside;
   hence, an insurrectionary separation; pref. se-, sed-, aside
   + itio a going, fr. ire, itum, to go. Cf. Issue.]
   1. The raising of commotion in a state, not amounting to
      insurrection; conduct tending to treason, but without an
      overt act; excitement of discontent against the
      government, or of resistance to lawful authority.
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            In soothing them, we nourish 'gainst our senate
            The cockle of rebellion, insolence, sedition.
                                                  --Shak.
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            Noisy demagogues who had been accused of sedition.
                                                  --Macaulay.
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   2. Dissension; division; schism. [Obs.]
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            Now the works of the flesh are manifest, . . .
            emulations, wrath, strife, seditions, heresies.
                                                  --Gal. v. 19,
                                                  20.
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   Syn: Insurrection; tumult; uproar; riot; rebellion; revolt.
        See Insurrection.
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WordNet (r) 3.0 (2006):

sedition
    n 1: an illegal action inciting resistance to lawful authority
         and tending to cause the disruption or overthrow of the
         government