trea ‧ son /ˈtriːz ə n/ BrE AmE noun [uncountable]
[ Date: 1100-1200 ; Language: Old French ; Origin: traison , from Latin traditio 'act of handing over or betraying' , from tradere ; ⇨ ↑ traitor ]
the crime of being disloyal to your country or its government, especially by helping its enemies or trying to remove the government using violence ⇨ treachery
treason against
Richter is accused of committing treason against the state.
The defendant was convicted of high treason (=treason of the worst kind) and sentenced to death.
—treasonable,
—treasonous adjective :
a treasonable act against the head of state