Quick Definition
ἀκάθαρτος, ον Adj unclean, impure
Strong's Definition
from 1 (as a negative particle) and a presumed derivative of 2508 (meaning cleansed); impure (ceremonially, morally (lewd) or specially, (demonic))
KJV Usage: foul, unclean
UBS Dictionary of the Greek New Testament
adjc. | -ον | ἀ- + καθαρίζω
53.39 · Religious Activities · Defile, Unclean, Common
defiled, ritually unclean pertaining to being ritually unacceptable, either as the result of defilement or because of the very nature of the object itself (for example, ritually unacceptable animals) It is possible that there is some subtle distinction in meaning, particularly on a connotative level, between κοινός[b] and ἀκάθαρτος in ACT 10:14, but it is difficult to determine the precise differences of meaning on the basis of existing contexts. The two terms are probably used in ACT 10:14 primarily for the sake of emphasis.
MAT 10:1 · MAT 12:43 · MRK 1:23 · MRK 1:26 · MRK 1:27 · MRK 3:11 · MRK 3:30 · MRK 5:2 · MRK 5:8 · MRK 5:13 · MRK 6:7 · MRK 7:25 · MRK 9:25 · LUK 4:33 · LUK 4:36 · LUK 6:18 · LUK 8:29 · LUK 9:42 · LUK 11:24 · ACT 5:16 · ACT 8:7 · ACT 10:14 · ACT 10:28 · ACT 11:8 · 1CO 7:14 · 2CO 6:17 · EPH 5:5 · REV 16:13 · REV 17:4 · REV 18:2 · REV 18:2 · REV 18:2
UBS Dictionary of the Greek New Testament © United Bible Societies, licensed CC BY-SA 4.0.
Thayer's Greek Lexicon
ἀκάθαρτος, -ov, (kabaipw), [fr. Soph. down], in the Sept. i. q. $V, not cleansed, unclean ; a. inaceremonial sense, that which must be abstained from according to the levitical law, lest impurity be contracted: Acts x. 14; xi. 8 (of food); Acts x. 28; 1 Co. vii. 14 (of men); 2 Co. vi. 17 (fr. Is. lii. 11, of things pertaining to idolatry); Rev. xviii. 2 (of birds). b. in a moral sense, unclean in thought and life (freq. in Plat.) : Eph. v. 5; τὰ ἀκάθαρτα τῆς πορνείας, Rev. xvii. 4 (ace. to the true reading); πνεύματα, demons, bad angels, [in twenty-three pass. of the Gospels, Acts, Rev.]: Mt. x. 1; xu. 43; Mk.i. 23, 26; i. 11, ete.; Lk. iv. 38, 36; vi. 18, ete.; Acts v. 16; viii. 7; Rev. xvi. 13; xviii. 2, (πνεύματα πονηρά in Mt. xii. 45; Lk. vii. 21; viii. 2; xi. 26; Acts xix. 12 sq. 15 sq.).
Mounce Concise Greek Dictionary
ἀκάθαρτος akathartos 32x
impure, unclean; lewd; foul
Abbott-Smith Greek Lexicon
ἀκάθαρτος, -ον
(< ἀ- neg., καθαίρω), [in LXX chiefly for טָמֵא;]
unclean, impure; physically (LS, MM, VGT, s.v.);
ceremonially: Ac 10:14, 28 11:8, I Co 7:14, II Co 6:17, Re 18:2;
morally: Eph 5:5, Re 17:4; c. πνεῦμα, as always in Gosp., Mt 10:1 12:43, Mk 1:23, 26, 27 3:11, 30 5:2, 8, 13 6:7 7:25 9:25, Lk 4:33, 36 6:18 8:29 9:42 11:24, Ac 5:16 8:7, Re 16:13 (cf. Cremer, 320).†
Moulton & Milligan — Vocabulary of the Greek NT
ἀκάθαρτος. The adjective is found in a moral sense of an unclean demon in the long magical papyrus P Par 5741°38 (= Se/ections, p. 113). It occurs in the correspondence of the architect Cleon (B.c. 255-4), P Petr II. 4, (3)§ (p. [8]), εἰλήφαμεν δὲ τοῦ ἀκαθάρτου kal τὸ [. . ., where the ganger Apollonius seems to be writing about a supply of iron for quarrymen, but the mutilation prevents our determining the reference. Vettius Valens, p. 761, has πάθεσιν ἀκαθάρτοις kal παρὰ φύσιν ἡδοναῖς, where the ethical sense is completely developed : half way comes Sy// 6338 (ii/A.D. according to Michel), where a Lycian named Xanthus dedicates a shrine to Mén Tyrannus and says καὶ [μηθένα] ἀκάθαρτον προσάγειν " καθαριζέστω δὲ ἀπὸ o(k)dpSwv καῇ Xotpéwy] κα[ὶ γ]υναικός --ἴῃξ impurity is ritual. ἀκαίρως. The well-known letter of a prodigal son, BGU III. 84614* (ii/A.D.) ( = Selections, p. 94) has the adverb ἀκαιρίως πάντα σοι διήγηται, ‘unseasonably related all to you.” For the adjective cf. Sy// 7301 (ii/B.c.) at λίαν ἄκαιροι δαπάναι. The derived noun appears in P Par 63** 356 (B.c. 165) διά τε τὴν περιέχουσάν pe (/. με) κατὰ πολλοὺς τρόπους ἀκ[αι]ρίαν.
Liddell-Scott-Jones — Greek-English Lexicon
ἀκάθαρτος (akathartos) — unclean. ἀκᾰθαρ-τος, ον, (καθαίρω) uncleansed, foul, ἀήρ[Refs 5th c.BC+] of the body, [Refs 5th c.BC+]; of a woman, quae menstrua non habet, [Refs 4th c.BC+]; of ceremonial impurity, [LXX] __b unpurified, [Refs 5th c.BC+]
2. morally unclean, impure, [Refs 5th c.BC+]thou beast! [Refs 3rd c.BC+]; ={μανιώδης}, [NT+5th c.BC+]. adverb ἀκαθάρτως, ἔχειν[Refs 5th c.BC+]
3. ofthings, notpurgedaway, unpurged, [Refs 5th c.BC+]
3. b unpruned, [Refs 4th c.BC+]
3. c ceremonially unclean, of food, [LXX+NT]
3. d not sifted, containing impurities, [Refs 3rd c.BC+]
II. active, not fit for cleansing, [φάρμακα] ἑλκέων ἀκαθαρτότερα[Refs 2nd c.AD+]