This is the 603rd most frequent Polish word.
św
"Św." is an abbreviation in Polish for "święty" (saint).
In this instance, "św" is used as part of a street name, standing for "święty" or "święta."
Ulica Św. Tomasza znajduje się w Krakowie.
St. Thomas Street is located in Krakow.
Here, "św" stands for "święty," and it's used informally to refer to St. Nicholas, traditionally known as Santa Claus.
Św. Mikołaj przychodzi do dzieci w grudniu.
Santa Claus comes to children in December.
Here, "św" is an abbreviation for "święty" meaning "Saint," and it's used to denote a revered person in a religious context.