The boukólos rule is a phonological rule of the

Proto-Indo-European language Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family. Its proposed features have been derived by linguistic reconstruction from documented Indo-European languages. No direct record of Proto-Indo-E ...

(PIE). It states that a labiovelar stop ()

dissimilate In phonology, particularly within historical linguistics Historical linguistics, also termed diachronic linguistics, is the scientific study of language change over time. Principal concerns of historical linguistics include: # to descri ...

s to an ordinary velar stop () next to the vowel or its corresponding glide . The rule is named after an example, the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

word (; from

Mycenaean Greek Mycenaean Greek is the most ancient attested form of the Greek language, on the Greek mainland and Crete in Mycenaean Greece (16th to 12th centuries BC), before the hypothesised Dorian invasion, often cited as the ''terminus ad quem'' for the ...

''qo-u-ko-ro'' /gʷou̯kolos/) "cowherd", ultimately from PIE , dissimilated from . If the labiovelar had not undergone dissimilation, the word should have turned out as *, as in the analogously constructed () "goatherd" < . The same dissimilated form is the ancestor of

Proto-Celtic Proto-Celtic, or Common Celtic, is the ancestral proto-language of all known Celtic languages, and a descendant of Proto-Indo-European. It is not attested in writing but has been partly Linguistic reconstruction, reconstructed through the compar ...

, the source of

Welsh Welsh may refer to: Related to Wales * Welsh, referring or related to Wales * Welsh language, a Brittonic Celtic language spoken in Wales * Welsh people People * Welsh (surname) * Sometimes used as a synonym for the ancient Britons (Celtic peop ...

(which would have had ''-b-'' rather than ''-g-'' if it had come from a form with *''-kʷ-'') and Irish , which is the common word for "boy" in the modern language. Another example could be the Greek negation (), which

Warren Cowgill Warren Cowgill (; December 19, 1929 – June 20, 1985) was an American linguist. He was a professor of linguistics at Yale University and the Encyclopædia Britannica's authority on Indo-European linguistics. Cowgill was unusual among Indo-Europea ...

has interpreted as coming from pre-Greek < , meaning approximately "not on your life". Without the boukólos rule, the result would have been * (). The rule is also found in Germanic, mainly in verbs, where labiovelars are delabialised by the epenthetic -u- inserted before syllabic resonants: * Old High German ("to come"), past participle ("come"), from Proto-Germanic and * Gothic , Old High German ("to see"), past plural OHG ("saw"), from Proto-Germanic and (''-g-'' results from earlier ''-k-'' through Verner's law)

References

Indo-European linguistics Sound laws {{historical-linguistics-stub