The boukólos rule is a
phonological
Phonology is the branch of linguistics that studies how languages or dialects systematically organize their sounds or, for sign languages, their constituent parts of signs. The term can also refer specifically to the sound or sign system of a ...
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 ()
dissimilates 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 p ...
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 th ...
''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 reconstructed through the comparative method. Proto-Celti ...
, the source of
Welsh (which would have had ''-b-'' rather than ''-g-'' if it had come from a form with *''-kʷ-'') and
Irish
Irish may refer to:
Common meanings
* Someone or something of, from, or related to:
** Ireland, an island situated off the north-western coast of continental Europe
***Éire, Irish language name for the isle
** Northern Ireland, a constituent unit ...
, which is the common word for "boy" in the modern language.
Another example could be the Greek negation (), which
Warren Cowgill 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
Verner's law describes a historical sound change in the Proto-Germanic language whereby consonants that would usually have been the voiceless fricatives , , , , , following an unstressed syllable, became the voiced fricatives , , , , . The law w ...
)
References
Indo-European linguistics
Sound laws
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