As Augustine says (Ep. xliii) and we find it stated in the Decretals (xxiv, qu. 3, can. Dixit Apostolus): "By no means should we accuse of heresy those who, however false and perverse their opinion may be, defend it without obstinate fervor, and seek the truth with careful anxiety, ready to mend their opinion, when they have found the truth," because, to wit, they do not make a choice in contradiction to the doctrine of the Church. Accordingly, certain doctors seem to have differed either in matters the holding of which in this or that way is of no consequence, so far as faith is concerned, or even in matters of faith, which were not as yet defined by the Church; although if anyone were obstinately to deny them after they had been defined by the authority of the universal Church, he would be deemed a heretic. This authority resides chiefly in the Sovereign Pontiff. For we read [Decret. xxiv, qu. 1, can. Quoties]: "Whenever a question of faith is in dispute, I think, that all our brethren and fellow bishops ought to refer the matter to none other than Peter, as being the source of their name and honor, against whose authority neither Jerome nor Augustine nor any of the holy doctors defended their opinion." Hence Jerome says (Exposit. Symbol [Among the supposititious works of St. Jerome]): "This, most blessed Pope, is the faith that we have been taught in the Catholic Church. If anything therein has been incorrectly or carelessly expressed, we beg that it may be set aright by you who hold the faith and see of Peter. If however this, our profession, be approved by the judgment of your apostleship, whoever may blame me, will prove that he himself is ignorant, or malicious, or even not a catholic but a heretic."- Aquinas, Summa Theologica, Second Part of the Second Part, Question 11, Article 2, Answer to Objection 3
Note that, sadly, most of Aquinas' answer depends on forged (or, at best, dubious) patristic quotations (not forged by Aquinas, but erroneously accepted by him). But yes, Aquinas did think it was possible for the "universal church" to define, in some sense, a doctrine. Furthermore, Aquinas viewed the Roman bishop as the chief residence of the universal church's authority.
This has some similarities to the modern Roman Catholic position on the development of doctrine, which does not itself require Aquinas to have held to dogmas that were only later "defined" (the same term is used, though we may wonder whether it has the same sense) later.