Lesson 4: The Grimm Brothers Make a Discovery or Why Sound Change Matters


This delightful TEDEd “onion” video by Gina Cooke offers some surprising etymological connections, but it also demonstrates how sound change is often at play and can reveal relationships among words. (She’ll have you consider in the video, for example, how the <o>s of one, onion, and alone are pronounced very differently even though the words actually are related.) Of course, we can’t possibly undertake a study of all of the sound changes that affected English for the last many hundreds of years. We can, however, look at a few that affected a great many words in systematic ways, thus revealing connections among words that we might not otherwise have noticed. The change known as Grimm’s Law, for example, actually affected the whole Germanic branch of languages (before there even was a language we call English). This change affected Dutch, German, Frisian, Swedish, and a bunch of others.


Jacob Grimm (who, along with his brother William collected the tales that became known as Grimm’s fairy tales) noticed that when there were certain sounds in Latin, there were certain other sounds in the Germanic languages, including English. In 1822, he published these sound correspondences, which then became known as Grimm’s Law. Here they are.


b → p

d → t

g → k


p → f

t → th

k → h


So <b> in Latin (and other non-Germanic Indo-European languages) became <p> in English (and other Germanic languages) and so on. It happened really systematically. And there were some other ones, but I include these since they are the ones that are most useful for our purposes. Because English, later in its life, borrowed so many words from Latin, Greek, and French, there are a great many words that are of non-Germanic origin that did not, therefore, undergo the Grimm’s Law sound shift (since it only affected the Germanic languages). For example, we have the English word tooth and the Latin root dent-, of dentist, dental, dentures, etc. So those "d"s turned into "t"s in English, but stayed "d"s in the languages that English later borrowed from. Some other examples:


d-t: decimal – ten, rodent - rat

g-k: grain – corn (remember we’re talking sound not spelling here)

p-f: patriarch – father

t-th: triple – three

k-h: cardiac – heart, cornucopia, unicorn - horn

b-p: bacillus – peg

(Ok, so there must be a better example of this b-p correspondence. A bacillus is “a straight rod-shaped bacterium that requires oxygen for growth”, according to Merriam-Webster. Maybe you find a better example of some word we have in English that start with "b" and has something to do with pegs, demonstrating an etymological connection.)


And if you compare other non-Germanic words from, say modern French and Spanish, with English ones, you can see the evidence for these sound changes here too; the word deux in French or dos in Spanish, both meaning ‘two.’ Or the words père in French or padre in Spanish, both meaning ‘father’. It’s pretty cool!


Learning a bit about Grimm’s Law diversion illustrates the importance of some sound changes to understanding connections among words.