"Hapax legomena" are quite common, as predicted by Zipf's law, which states that the frequency of any word in a work (corpus) is inversely related to its rank in the frequency table. For large corpora, about 40% to 60% of the words (counting by type) are "hapax legomena", and another 10% to 15% are "dis legomena". In the Brown Corpus of American English, about half of the 50,000 words are "hapax legomena" within that corpus.