ELI5: Explain Like I'm 5

Lexicostatistics

Lexicostatistics is a way to compare different languages. It involves counting up the number of words in different languages that have the same or similar meanings. Scientists then use these numbers to measure how closely related those languages are. For example, if two languages have a lot of words that mean the same thing, it suggests that those two languages may have come from the same source or that people who spoke them were in contact a lot.