decapitation (n.)

1640s, "act or fact of decapitating or being decapitated," from French décapitation, from Medieval Latin decapitationem (nominative decapitatio), noun of action from past-participle stem of Late Latin decapitare, from Latin de "off" (see de-) + caput (genitive capitis) "head" (from PIE root *kaput- "head"). In U.S. political slang, "summary removal from office," 1869.