Treason

Old French traison, from Latin traditio — a handing over, betrayal. From tradere — to hand over (the same root as 'tradition'). Originally meant simply betrayal; acquired its specific political meaning in medieval law.

The US Constitution defines treason narrowly: 'levying War against them, or in adhering to their Enemies, giving them Aid and Comfort.' The framers deliberately made it hard to charge — they had seen treason accusations used as political weapons in England. In American political speech, 'treason' is invoked frequently and charged almost never. The gap between the accusation and the constitutional definition is where most political uses of the word live.