While researching the etymology of the word "fave", a noun that's in the process of being verbed,¹ I noticed that, according to Google's ngram viewer, the word was much more popular in the 1600-1700s than it is now.

A bit of investigation reveals that Google's book-scanning software is at fault; it can't recognize the long s commonly used in books prior to the 1800s. So each time it encounters "save" with a long s, it sees "fave":

1. "Fave" (n., adj.) is slang for "favorite", a usage that started in the US in the 1920s, as in "Teddy Roosevelt was totally my fave President". Recently, "fave" (v.) has come to mean liking or marking an item as a favorite on social media services like Twitter, Flickr, Facebook, Tumblr, Stellar, etc. (IMPORTANT: It's "fave", not "fav". Let's get this one right, people.)↩

• Google Books
• language
• typography