The name Merryn is a girl's name of Cornish origin. Merryn and is often added to lists like Cornish Baby Names and discussed in our forums with posts like "Love, Like, Lose -- Outlandish/Guilty Pleasures edition!".
From the experts:
St. Merryn, the name of a Cornish town derived from Mirin, a 6th century Irish saint important in Scottish history often as Mirren, is sometimes used in modern times as a girl's name. Lovely, sleek, shimmery feel though many will assume it's invented until you enlighten them on its long history. Also spelled Meryn.