A complete list of spelling differences between American and British English, assuming such a list could be compiled, would be a daunting and not particularly useful thing. For example, among many other factors, it would have to take account of differences of hyphenation and spacing in compound words (US antiaircraft/GB anti-aircraft, US bookkeeper/GB book-keeper, US ultramodern/GB ultra-modern, and so on). Since American English tends to drop the hyphen much faster than British English, this factor alone would make the list potentially endless. The difficulties arising from hyphenation also illustrate the complexity of the subject in general, for not only do variant spellings exist for many words on both sides of the Atlantic, often the authorities in each country—i.e. the dictionary-makers —are in disagreement as to which spelling of a word is to be preferred over other possibilities. Rather than attempt a complete inventory of spelling differences, then, we have chosen to identify a number of broad categories. The following lists are illustrative rather than exhaustive. One important point should be noted: if two versions of a word are given as accepted US or GB spelling, the first is the preferred spelling and the second a variant. (Our authorities are Merriam- Webster's Collegiate Dictionary for American words and the Concise Oxford Dictionary for British.) To see the content, click here.