Zipf's law
Definition - A law that states that given a corpus of natural-language utterances a word of a certain frequency will occur approximately twice as often as the next most frequent word.

Example -
The word the is the most frequently occurring word in the Brown Corpus, accounting for nearly 7% of all word occurrences. The next-most-frequent word is of, which accounts for slightly over 3.5% of all word occurrences.

Etymology -
The law is named after the linguist George Kingsley Zipf who first proposed it in 1935.

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