In Vatican II’s 1963 Constitution on the Sacred Liturgy (n. 53), it was called by two names: the “Oratio communis” (“Common Prayer”) or the “Oratio fidelium” (“Prayer of the Faithful”).
In the 1964 instruction on the liturgy Inter Oecumenici, the two names given (in English) are “universal prayer” and “prayer of the faithful”. (n. 56)
In Pope Paul VI’s 1969 Apostolic Constitution Missale Romanum, he uses the names from the Vatican II document.
The modern General Instruction of the Roman Missal calls it the “Prayer of the Faithful” throughout. This seems to be the preferred title since 1969.
I’ve also heard it called the “General Intercessions”.