noun
: a usually mandatory oath affirming the loyalty of its taker (as to a sovereign, government, or party principles)
ruled the Genevese … with the help of loyalty oaths and the gibbet — Times Literary Supplement
the loyalty oath will be abandoned at the next Democratic convention — Newsweek
especially : an oath often required of public employees or applicants for public employment in the United States typically affirming that the signer upholds the United States or state constitutions and is not knowingly a member of any of a number of organizations held to be subversive