- Old High German Karl > Early Proto-Slavic *kȁrlju (substantivized possessive adjective) > *kȁrlji (umlaut *u > *i) > *karlji̍ (Dybo's law) > *korlji̍ (change of *a to *o) > *korljь̍ (change of *i > *ь) > *korl'ь̍ (iotation of *lj > *l') > *kõrl'ь (neoacute due to Ivšić's law).
The shift from hard o-stem to the soft jo-stem, as outlined in the chronology above, has several theories of origin:
- Holzer explains the j-suffix as originating from a substantivized possessive adjective
- Schenker suggests analogical replacement after agent nouns ending in *-teljь or other words denoting leaders such as *cěsarjь and *kъnędzь
- Pronk-Tiethoff suggests the final *-ljь is due to the fact that Proto-Slavs likely perceived the Old High German final consonant as soft, similarly as in the loanword *grędeljь.
The word has been described as "without doubt the most famous Germanic loanword in Slavic" (Pronk-Tiethoff 2013) due to the fact that it's the only loanword in Slavic that can actually be dated, thus giving clues to the absolute dating of Proto-Slavic phonological developments. The fact that it regularly underwent historical Proto-Slavic sound laws, and that it's reflected in all three branches, is one of the chief indications to date Late Proto-Slavic (Common Slavic) to the ninth century.
However, this is comparatively late (only a century before Old Church Slavonic manuscripts were written), so other etymologies have been suggested:
- Holzer derives it from the name of the Frankish ruler Charles Martel (688-741). The issue with this theory is that Charles Martel was not particularly important to the contemporary Slavs.
- Stender-Petersen derives it from Proto-Germanic *kar(i)laz (“free man”) (Old High German karl (“man”)) with a semantic shift explained as "very ordinary".
These theories are generally thought of as less convincing than from Karl "Charlemagne", who was an actual king of (some) Slavs.
- East Slavic:
- South Slavic:
- West Slavic:
- Vasmer, Max (1964–1973), “король”, in Etimologičeskij slovarʹ russkovo jazyka [Etymological Dictionary of the Russian Language] (in Russian), translated from German and supplemented by Trubačev O. N., Moscow: Progress
- Trubačev O. N., editor (1984), “*korl'ь”, in Etimologičeskij slovarʹ slavjanskix jazykov [Etymological dictionary of Slavic languages] (in Russian), volume 11, Moscow: Nauka, page 82ff
- Saskia Pronk-Tiethoff (2013), The Germanic loanwords in Proto-Slavic, Rodopi: Amsterdam/New York, page 111ff