I’m not making this stuff up. I’m getting my information from Catholic sources.
jimmyakin.org/2004/06/two_instances_o.html
“If you see a pope say “we define” or “I define,” it is a signal that he is making a definition and thus exercising the Church’s gift of infallibility. (This is not the only way in which he can do this, but it is the standard way.)”
Pope Boniface VIII in his Papal Bull Unam Sanctam (A.D. 1302): “We declare, say,
define, and pronounce that it is absolutely necessary for the salvation of every human creature to be subject to the Roman Pontiff.”
New Advent says that an ecumenical council approved by the pope is an organ of infallibility.
newadvent.org/cathen/07790a.htm
Ecumenical councils
1 An ecumenical or general, as distinguished from a particular or provincial council, is an assembly of bishops which juridically represents the universal Church as hierarchically constituted by Christ; and, since the primacy of Peter and of his successor, the pope, is an essential feature in the hierarchical constitution of the Church, it follows that
there can be no such thing as an ecumenical council independent of, or in opposition to, the pope. No body can perform a strictly corporate function validly without the consent and co-operation of its head. Hence:
• the right to summon an ecumenical council belongs properly to the pope alone, though by his express or presumed consent given ante or post factum, the summons may be issued, as in the case of most of the early councils, in the name of the civil authority. For ecumenicity in the adequate sense all the bishops of the world in communion with the Holy See should be summoned, but it is not required that all or even a majority should be present.
• As regards the conduct of the deliberations, the right of presidency, of course, belongs to the pope or his representative; while as regards the decisions arrived at unanimity is not required.
• Finally, papal approbation is required to give ecumenical value and authority to conciliar decrees, and this must be subsequent to conciliar action, unless the pope, by his personal presence and conscience, has already given his official ratification (for details see GENERAL COUNCILS).
2 That an ecumenical council which satisfies the conditions above stated is an organ of infallibility will not be denied by anyone who admits that the Church is endowed with infallible doctrinal authority. How, if not through such an organ, could infallible authority effectively express itself, unless indeed through the pope?