“At one level, few things are simpler than a dictionary: a list of the words people use or have used, with an explanation of what those words mean, or have meant. At the level that matters, though – the level that lexicographers fret and obsess about – few things could be more complex. Who used those words, where and when? How do you know? Which words do you include, and on what basis? How do you tease apart this sense from that? And what is “English” anyway?
In the case of a dictionary such as the OED – which claims to provide a “definitive” record of every single word in the language from 1000AD to the present day – the question is even larger: can a living language be comprehensively mapped, surveyed and described? Speaking to lexicographers makes one wary of using the word “literally”, but a definitive dictionary is, literally, impossible. No sooner have you reached the summit of the mountain than it has expanded another hundred feet. Then you realise it’s not even one mountain, but an interlocking series of ranges marching across the Earth. (In the age of “global English”, the metaphor seems apt.)”