On Shavuot

"Shalosh" means three or rather, three of something. "Regalim" is the plural of "regal" meaning foot. So literally, it means "three feet." Specifically, the word foot here is used to refer to traveling to Jerusalem (on foot) on the 3 annual pilgrimage festivals of Pesach (Passover), Shavuot (Pentecost or the Feast of Weeks) and Succot (the Feast of Booths).

Shalosh means three

creatures of habit = yetsurim shel ha regalim (יצורים של הרגלים)

שלוש עשרה (shalosh esreh)