Today it used as a pejorative to "describe" those who adhere to traditional Catholicism. It includes those who separate the Holy See from the governance of Catholic faith, especially where it concerns the Latin rite Mass and the controversy between the Normative Mass, and the Mass of the 1962 Missal, but also is used toward some who believe and practice traditional Catholicism.
It is also used to describe extreme Islamism.
“…we are witnesses today of a new integralism that may seem to support what is strictly Catholic but in reality corrupts it to the core. It produces a passion of suspicions, the animosity of which is far from the spirit of the gospel. There is an obsession with the letter that regards the liturgy of the Church as invalid [read: not legitimate or theologically suspect] and thus puts itself outside the Church. It is forgotten here that the validity of the liturgy depends primarily, not on specific words, but on the community of the Church; under the pretext of Catholicism, the very principle of Catholicism is denied, and, to a large extent, custom is substituted for truth.” Joseph Cardinal Ratzinger, Principles of Catholic Theology (1982), p. 377