The word *wĺ̥kʷos is a thematic accented zero-grade noun perhaps derived from the adjective *wl̥kʷós (“dangerous”); compare Hittite 𒉿𒀠𒆪𒉿 (walkuwa, “dangerous”), Old Irish olc (“evil”), Sanskrit अवृक (avṛká, “safe”, literally “not wild”), वृकतात् (vṛká-tāt, “savagery”). Stress shift onto the zero-grade is consistent with nominalized adjectives: compare Sanskrit कृष्ण (kṛ́ṣṇa, “black antelope”) from कृष्ण (kṛṣṇá, “black”). Alternatively, the word may be a derivative of the verbal root *welh₂- (“to tear up”). In either case, the word's formation closely resembles that of *h₂ŕ̥tḱos (“bear”), another thematic accented zero-grade noun whose referent is an animal subject to cultural taboos.
The Latin and Greek reflexes are unexpected (vs. expected Lat *volquus, Gk *álpos, according to the regular progression PIE *l̥ > Lat ol, Gk al). The Latin reflex is a borrowing from Osco-Umbrian (where PIE */kʷ/ regularly gave /p/), and both the Italic and Greek reflexes underwent metathesis, possibly as a taboo deformation meant to offset the fear usually associated with the animal. A deformation would explain the metathesis of */w/ and */l/, which also occurred in Greek (*wĺ̥kʷos → *lúkʷos → *lúkos), and also explains the presence of delabialized /k/ per the boukólos rule (regardless of whether it is Proto-Indo-European already or only Proto-Greek). In both cases, the expected forms are so close to the word for “fox” – compare Latin volpēs, Ancient Greek ἀλωπός (alōpós), ἀλώπηξ (alṓpēx) – that avoiding conflation of the two words “wolf” and “fox” may have motivated either alteration or borrowing.
The Germanic reflex, with /f/ < */p/ < */kʷ/, underwent an unusual sound change, but the velar was retained in at least one form, i. e. Old Norse ylgr (“she-wolf”) (vs. Old English wylf, Middle High German wülpe < *wulbī) < *wulgʷī́ < *wl̥kʷíh₂, which indicates neither taboo deformation nor derivation from some other root took place.
Armenian and Celtic have replaced the word with Proto-Indo-European *waylos (“howler”) due to taboo; compare Old Armenian գայլ (gayl), Middle Irish fáel. (In Celtic, *kū (“hound, dog”) is also used to designate the wolf.)
*wĺ̥kʷos m (non-ablauting)
- Old Albanian: ulk
- Albanian: ujk
- Luwian: *𒉿𒀠𒉿 (*walwa/i, “lion”) (only attested in personal names)
- Lydian: walw-el(i) "lion-like, pertaining to lions"
- Balto-Slavic: *wilkas (see there for further descendants)
- Slavic: *vьlkъ (see there for further descendants)
- Celtic: *ulkʷos (see there for further descendants)
- Germanic: *wulfaz (see there for further descendants)
- Hellenic: *lúkos
- Indo-Iranian: *wŕ̥kas (see there for further descendants)
- Italic: *lukʷos
- Latin: lupus (possibly through Osco-Umbrian) (see there for further descendants)
- Paeonian: Λυκκ- (Lukk-), Λυκπ- (Lukp-) (< *lukʷos)
- Tocharian: *wä́lkʷë
- Tocharian B: walkwe
- ^ A. Lehrman, “Anatolian Cognates of the PIE Word for ‘Wolf’”, Die Sprache 33 (1987), 13–18.
- ^ Tamaz Gamkrelidze & Vjačeslav Ivanov, Indo-European and the Indo-Europeans (Tbilisi: Tbilisi UP, 1984), 492.
- ^ J. P. Mallory & D. Q. Adams, Encyclopedia of Indo-European Culture (London: Fitzroy Dearborn, 1997), s. v. “wolf”, 646.
- ^ Martirosyan, Hrach (2010) Etymological Dictionary of the Armenian Inherited Lexicon (Leiden Indo-European Etymological Dictionary Series; 8), Leiden, Boston: Brill, page 196.