Synonyms for Treason (same or very similar meaning)
WordNet sense 1 (disloyalty by virtue of subversive behavior):
subversiveness, traitorousnessWordNet sense 2 (a crime that undermines the offender's government):
high treason, lese majestyWordNet sense 3 (an act of deliberate betrayal):
betrayal, perfidy, treacheryFrom the ODE community, based on WordNetadd/edit