What is the ruling on calling someone a saint if that it what they are typically referred to, eg "Saint Jerome"?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

The word "saint" literally denotes purity; it implies praise and, therefore, it is impermissible for a Muslim to use it to refer to a disbeliever unless it is used to mention such a person according to a title by which he is commonly known for the sake of distinction.

This is how we can understand why Muslim scholars used the title "Saint" in their references to some Christians in their writings. For instance, Shaykh Al-Islaam Ibn Taymiyyah wrote, "No one has said that they would say that their idols create, give life and bring about sustenance; rather, they worshipped them for their need of them like the case with the polytheists who visit the venerated graves and the Christians who revere the icons of saints, taking them as intercessors, mediators and intermediaries." [Mukhtasar Al-Fataawa Al-Misriyyah]

Allaah Knows best.