So, word frequency is pretty important?
Yes and no. Word frequency is not a perfect predictor of word difficulty nor can it always tell us the importance of a word in a text, but it is one of the easiest and best ways to estimate how likely a given word will be known. The assumption is that high frequency words are easier to understand because they are used most often and, because of their numerical dominance, more important to all aspects of language. This idea has been the basis of many studies for about 100 years. One of the earliest and most extensive compilations of word frequency for its time was Thorndike’s The Teacher’s Word Book (1921). Thorndike, and others of that time, routinely substituted the term most frequent for most important but does note that frequency… …is not a perfect measure of the importance of words, for two reasons. First, a word may be very important for a pupil or graduate to know and yet not figure largely in the world’s reading. Second, tens of thousands of hours of further counting would be re
