violation or betrayal of the allegiance that people owe to their sovereign or their country, esp by attempting to overthrow the government; high treason
2.
any treachery or betrayal
Derived forms
treasonable (ˈtreasonable) or treasonous (ˈtreasonous)
adjective
treasonableness (ˈtreasonableness)
noun
treasonably (ˈtreasonably)
adverb
Word origin
C13: from Old French traïson, from Latin trāditiō a handing over; see tradition, traditor