Researchers conducted an analysis of more than 10 million words in English, Spanish and Hebrew texts from 1800 to 2008 that had been digitized by Google.
"We are now able to analyze language comprising not only the common words, but also the extremely rare words, and not just for yesterday but for yesteryear, and not just for yesteryear, but back to a time before most people can track their family lineage," researcher Alexander Petersen of the Lucca Institute for Advanced Studies in Italy told LiveScience.com.
The study focused on fluctuations of how often words were used and how often they "died," or fell out of common use.
"Words don't actually die -- they only disappear in a statistical sense," Petersen said. "Unlike animal species, which undergo irreversible extinction, words can come in and out of use."
While words have died at a faster rate in the past 10 to 20 years than in all the time measured before, languages are also seeing fewer entirely new words emerge, researchers said.
Automatic spell-checkers may be partly responsible for that, they said, killing misspelled or unusual counterparts of accepted words before they see print.
After about 40 years, new words either see enough use to get accepted into a language or largely are abandoned, the study found.
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