Treason

This word imports a betraying, treachery, or breach of allegiance.

The Constitution of the United States, Art. III, defines treason against the United States to consist only in levying war against them, or in adhering to their enemies, giving them aid or comfort. This offence is punished with death. By the same article of the Constitution, no person shall be convicted of treason, unless on the testimony of two witnesses to the same overt act, or on confession in open court.
   

This entry contains material from Bouvier's Legal Dictionary, a work published in the 1850's.

To aid or enlist with a state enemy or to attempt or conspire to harm the head of state, such as a king, queen or president. - (read more on Treason)