"A magisterium is the power to determine and teach the truth of what group members believe"
https://catholicstand.com/magisterium-blessing-or-curse/
"The magisterium is the official teaching office of the Church, including the pope and the bishops in union with him."
https://aleteia.org/2020/07/02/what-is-the-magisterium-of-the-catholic-church/
"The magisterium of the Catholic Church is the church’s authority or office to give authentic interpretation of the Word of God, “whether in its written form or in the form of Tradition.” According to the 1992 Catechism of the Catholic Church , the task of interpretation is vested uniquely in the Pope and the bishops"
https://elrenosacredheart.com/question-answer/what-is-the-magisterium-of-the-catholic-church.html
"Since he doesn’t accept Catholic teaching on the infallibility of the Magisterium and the Church’s freedom from error, he is comfortable with a pseudo-magisterium that consistently teaches heresy, false doctrine and leads people to Hell."
https://vaticancatholic.com/the-magisterium/