Lettered words are new borrowings and native creations in Chinese written fully or partly with Roman letters. Lettered words in which the letters fit into the Chinese visual ‘frame’ of writing, the ‘equidimensional square’, are adopted “as is,” bypassing traditional borrowing processes that employ Chinese morpheme-syllable-characters (<i>zì</i>). These include primarily initialisms, since each letter fits into one frame. Compounds containing a Roman letter as a morpheme (<i>X</i> in <i>X-ray</i>) are adapted as hybrid words that retain the letter morpheme. We hypothesize that lettered words are shorter than English words on average and use primarily upper case letters. We conducted a corpus study of lettered words in Chinese newswires to test these assumptions, finding that shorter words are most frequent, upper case is preferred, and initialisms are most common. We conclude that Roman letters are a new set of <i>zì</i> that can now be used to form words in Chinese.