What does "shoheen" mean?

My choir is singing a lullaby called "Shoheen" and no one knows what it means. I know there's an Irish folk song called "Shoheen Sho" (and I don't know what that means either) but this is not the Irish song. Here's a quote from the lyrics: "Sleep, little loved one, safe and warm, Shoheen, Shoheen, lo." Any ideas?