It's supposed to be the motto of Jesus College, Oxford but I can't find any reference to it on their web site. I'll try to remember to have a look at work (an Oxford Univ. library!) tomorrow. We've got a latin expert at work too.
Mr Mistoffelees - you had me foxed there! The arms shown on the OED are the Oxford University arms but the motto that you quoted isn't the OU motto.
So I had a look (I'm surrounded by examples of the OU arms!) and the riddle is quite easily solved! The OU motto (as FE pointed out) is "Dominus Illuminatio Mea" but it is written on two pages. You've read across the open book but the words are written down one page, then down the facing page, so in fact the OED logo reads "Dominus Illuminatio Mea" not "domimina nustio illumea"!