My cat is named Minnaloushe after Yeats’s poem, although he goes by Minnow. When I address him in French, I call him Minou ("mee-nu"), the generic kitty. Minnow/Minou derives from a root meaning small. I don't know where "-loushe" originally came from, but I'm guessing "lux" (light,
Lucius). “Louche” means shady in the sense of disreputable. So when I call Minnow Minnaloushe, I'm either calling him "Little Light" or "Slim Shady"! Overall, I’d say the best interpretation is “Naughty Little Thing,” which is definitely accurate for my Minnow.