Saint, in a Catholic sense, of course.
What are the processes needed to determine whether the soul of the person is worthy of going into heaven (or purgatory, in which case the person won’t be declared a saint, I presume)?
The goal of the process is to determine whether a soul is worthy to veneration by the universal Church or not.
The first step is to scrutinize his/her life, and if nothing is found against him, the Church declares the person
venerable: people may pray for his intercession.
It there is enough prayer, and the prayers and the intercession of the venerable soul results a proven miracle, the person is promoted to be
blessed, which means that certain communities can create official celebration: Mass and Office for him.
If the amount of prayers for intercession are increasing and at least a second proven miracle follows attributed to the intercession of the blessed soul, then the soul is promoted to
saint, which means that any community in the earth can make officium and mass for his celebration.
For some cases the pope promotes the celebration as part of the universal calendar, so the whole Church should celebrate the saint.
The process is costly, so only those go through, who have sufficient influence. It is not an accident that most of the second millennium saints are religious, kings or similar souls, members off affluent groups.
This process has probably little to do with the heavenly order, that is retained to God.