I would have to recommed Rhisiart Hincks' Welsh-Breton dictionary. (Geiriadur Cymraeg-Llydaweg.) Even if you don't speak a word of Breton. This is mostly because it contains a lot of words that are in no other dictionary, reassuring you that they are not typos. Often, it also lists the more formal/literary form which you can go back and look up in your Geiriadur Mawr. It also tells you whether a form is North Welsh or South Welsh, and which is the more common, and has the handiest verb conjugation chart ever in the front, again listing literary and spoken forms, with the most standard spoken forms in boldface type. Also, it contains a lot of the words borrowed from English and place names. Example, verb DOD: 1. deuthum 1. DES I, (n:) dois i, (s:) dethim i, (s:) desim i, etc. 2. daethost 2. DEST TI, (n:) doist ti 3. daeth 3. DAETH E/HI, doeth e/hi, (n:) doth o/hi --Antone