A quick google search yeilds 1 million words as a max estimate for the number of words in the English language, including archaic and scientific words. But half of those are too technical and domain specific and remained unchronicled in oxford. Multiply that by about 10 for all the forms of a word. (I'm not sure about this figure). Then multiply that by about 5.1 for the average word length. Thats still only 510 million bytes. Not even a gig.