Some names are sufficiently unique not to suffer reappearance issues. "Ku Klux Klan" first appears in the 1860s, and has since been in regular use. "Elvis Presley" does not appear until the 1950s, but it has been up, up and away ever since. Occasionally, a word may have a temporary vogue. It appears then disappears. In 1930, when Turkey was renaming its capital city, Dominican Republic dictator Rafael Trujillo was doing the same with his. He modestly renamed the Dominican capital of Santo Domingo - "Trujillo City." When Trujillo was overthrown and assassinated in 1961, his countrymen quickly restored the capital to its historic name. The graph on this page shows the rise and fall of "Trujillo City," at least as it appeared in books. It looks the same as the career of Trujillo himself. It should be noted that even in its heyday, "Trujillo City" was never as common in books as "Santo Domingo."
Then there is the case of old usage. Back in the day, the letter "s" was commonly written "f." Since Google Books is based on scans, all of those old "s's" show up as "f's." So, the word "stuff" frequently was written "ftuff." Ngrams shows regular appearances of "ftuff" from the early days to a peak in the late 1700s. Then it drops precipitously, virtually disappearing by 1820.
We should note that there are some similarities and differences between this and the "Get Keywords" feature available to subscribers of this site's AE Bibliographic Database. Rather than looking at all records for the frequency of appearance of selected keywords, "Get Keywords" allows you to select certain bibliographic records to determine which words appear most frequently within them. Its specific purpose is to show collectors what related words are logical to search for online when looking for material related to their collection, and to inform booksellers as to what keywords should appear in their online listings for a particular title. We are not sure what specific purpose Ngrams can be used for, and it was not designed with a particular purpose in mind. Nevertheless, we expect specific practical uses will evolve, and until then, Ngrams is both informative and fun to use. Try it out!
Google's Ngrams can be found at the following link: http://ngrams.googlelabs.com.
