The name Swithun is a boy's name of English origin meaning "quick, strong". Swithun and is often added to lists like Unique Baby Names: Unusual and Rare and discussed in our forums with posts like ""Down the Rabbit Hole": The Game of Bad Names".
From the experts:
Variously spelled Swithun or Swithin, and associated with St. Swithin's day, July 15th, which is famous as a weather predictor a la Groundhog's Day: supposedly, the weather on his feast day will continue for forty days. This would certainly make a unique choice.