Quick Definition
λύκος, ου, ὁ n.m. a wolf, jackal
Strong's Definition
perhaps akin to the base of 3022 (from the whitish hair); a wolf
KJV Usage: wolf
UBS Dictionary of the Greek New Testament
noun, m. | -ου
4.11 · Animals · Animals
wolf wild, four-footed, predatory canine; light-brown fur, similar to jackal, but much bigger; Canis lupus; regarded as ravenous and fierce; commonly prey on flocks; symbol of roaming, opportunistic, dangerous, fierce, and clever banditry In areas of the world in which wolves are not known, some translators have rendered λύκος[a] by the local equivalent of ‘leopard’ or ‘jaguar.’ This may be satisfactory for initial translations of the Scriptures, but such shifts in reference are normally rejected at a later stage by those readers who become more acquainted with the types animals which exist in other parts of the world. In most instances in which local terms for ‘wolf’ do not exist, translators have used descriptive phrases such as ‘wild dog’ or ‘fierce, wild dog,’ or they may have borrowed a term from a dominant language in the area and have added a qualifying phrase, for example, ‘a wild animal called wolf.’ One may, of course, simply use a more generic expression with some kind of qualifier. For example, in ACT 20:29 it is possible to use ‘fierce, wild animals,’ for the meaning of the passage is primarily figurative, and a specific designation of wolf is not required.
88.121 · Moral and Ethical Qualities and Related Behavior · Bad, Evil, Harmful, Damaging
vicious person, fierce wolf, fierce person (a figurative extension of meaning of λύκος[a] ‘wolf,’ 4.11) a person who is particularly vicious and dangerous In situations where wolves are not known, it may be possible to translate ACT 20:29 as ‘men like fierce animals will come among you.’ In some instances λύκος in ACT 20:29 has been rendered as ‘fierce, wild dogs.’
UBS Dictionary of the Greek New Testament © United Bible Societies, licensed CC BY-SA 4.0.
Thayer's Greek Lexicon
λύκος, -ov, 6, Hebr. 381, a wolf: Mt. x. 16; Lk. x. 3; Jn. x. 12; applied figuratively to cruel, greedy, rapacious, destructive men: Mt. vii. 15; Acts xx. 29; (used trop. even in Hom. I]. 4,471; 16, 156; in the O. T., Ezek. xxii. 27; Zeph. iii. 3; Jer. v. 6).
Mounce Concise Greek Dictionary
λύκος lykos 6x
a wolf, Mt. 10:16; Lk. 10:3; Jn. 10:12; met. a person of wolf-like character, Mt. 7:15; Acts 20:29*
Abbott-Smith Greek Lexicon
λύκος, -ου, ὁ,
[in LXX for זְאֵב;]
a wolf: Mt 10:16, Lk 10:3, Jo 10:12; fig. (as Ez 22:27, Ze 3:3, Je 5:6, al.), Mt 7:1, Ac 20:29.†
Moulton & Milligan — Vocabulary of the Greek NT
λύκος. P Par 619 (B.c. 129) συνέβη δὲ καί, διὰ τὸ ἀχ[ανῆ] τὴν θύραν ἀφεθῆν[αι, ὑπὸ] λύκων AvpavOA[var] ἀγαθὰ σώματα [περ]ιβρωθέντα, ‘‘and it also happened that, owing to the door having been left open, certain bodies in good condition were mangled by wolves, which have partly devoured them.” The Latin (or rather Sabine) /ufus is linked with λύκος, and points to an original *luqzos, MGr λύκος.
Liddell-Scott-Jones — Greek-English Lexicon
λύκος (lukos) — wolf. λύκος [ῠ], ὁ, wolf, [Refs 8th c.BC+]; πολιός grisly,[Refs 8th c.BC+]; ὀρέστεροι[Refs 8th c.BC+]; the small Egyptian wolves mentioned by [Refs 5th c.BC+] were perhaps jackals: various kinds distinguished by [Refs 3rd c.AD+] to see a wolf, i. e. to be struck dumb, as was vulgarly believed of any one at whom a wolf got the first look [Refs 5th c.BC+]; λύκου πτερά, of things that are not, 'pigeon's milk', [Refs]; ὡς λ. χανών, of vain expectation, [Refs 5th c.BC+]; πρίν κεν λ. οἶν ὑμεναιοῖ, of an impossibility, [Refs 8th c.BC+]; ὡς λύκοι ἄρν᾽ ἀγαπῶσιν, of treacherous or unnatural love, poetical cited in [Refs 5th c.BC+]; λύκου βίον ζῆν, i. e. live by rapine, Prov. cited in [Refs 2nd c.BC+]; ἐκ λύκου στόματος, of getting a thing praeter spem, [Refs 2nd c.AD+]; τῶν ὤτων ἔχειν τὸν λύκον 'catch a Tartar', [Refs 4th c.BC+]; λ. ἀετὸν φεύγει, of the inescapable, [Refs 4th c.AD+]
II. a kind of daw, [Refs 4th c.BC+]; compare λύκιος.
III. a fish, ={καλλιώνυμος}, [Refs 1st c.BC+]
IV. a kind of spider, [Refs 4th c.BC+]
V. anything shaped like a hook:
V.1. a jagged bit for hard-mouthed horses, Latin lupus, [Refs 1st c.AD+]; compare λυκοσπάς.
V.2. hook or knocker on a door, [Refs 5th c.AD+]
V.3. flesh-hook, [Refs 2nd c.AD+]
VI. nickname of παιδερασταί, [Refs 5th c.BC+]
VII. the flower of the iris, Philin. cited in [Refs 2nd c.AD+]
VIII. a kind of noose, [Refs 2nd c.AD+]
IX. a pastille used in dysentery, [Refs 6th c.AD+]
X. ={ὀροβάγχη}, variant in marginal of [Refs 1st c.AD+]
XI. an engine of war for defending gates, [Refs 6th c.AD+]. (Cf. Sanskrit vŕ[null]kas, Lithuanian vi[ltilde]kas, Slavonic vl[ucaron]k[ucaron], Gothic wulfs.)