St

The abbreviation sits directly before a holy person's name, as in St Peter or St Paul. When a single dedication honors two saints together, the plural takes over: Sts Peter and Paul, or the doubled-letter form SS. Julia M. H. Smith's Europe after Rome (2005) writes Sts for the church Augustine founded at Canterbury, dedicated to Peter and Paul as a pair.

Here the weekday borrows a shortening that ordinarily belongs to the saint's title, which is why it counts as nonstandard. A column of days in a timetable or planner makes the meaning clear. In running prose, readers will reach for the saint first, so the safer choice there is to spell out Saturday.