Quick Definition
inextinguishable, unquenchable
Strong's Definition
not extinguished, i.e. (by implication) perpetual
Derivation: from G1 (Α) (as a negative particle) and a derivative of G4570 (σβέννυμι);
KJV Usage: not to be quenched, unquenchable
Thayer's Greek Lexicon
ἄσβεστος, ἄσβεστον (σβέννυμι), unquenched (Ovid,inexstinctus), unquenchable (Vulg.inexstinguibilis): πῦρ, Mat_3:12; Luk_3:17; Mar_9:43, and R G L brackets in 45. (Often in Homer; πῦρ ἄσβεστος of the perpetual fire of Vesta, Dionysius Halicarnassus, Antiquities 1, 76; (of the fire on the altar, Philo de ebriet. § 34 (Mang. i. 378); de vict. off. § 5 (Mang. 2:254); of the fire of the magi, Strabo 15 (3) 15; see also Plutarch, symp. 50:7, probl. 4; Aelian nat. an. 5, 3; cf. Heinichen on Eusebius, h. e. 6, 41, 15).)
Mounce Concise Greek Dictionary
ἄσβεστος asbestos 3x
unquenched; inextinguishable, unquenchable, Mat_3:12 ; Mar_9:43 ; Luk_3:17
Abbott-Smith Greek Lexicon
ἄ -σβεστος , -ον
( <σβέννυμι ),
[in LXX for H5301 H3808 , Job_20:26 ΰ 3 A (ἄκαυστον, ΰ 2 B ) * ;]
unquenched, unquenchable: πῦρ , Mat_3:12 , Mar_9:43 , Luk_3:17 .†
Liddell-Scott — Intermediate Greek Lexicon
ἄσβεστος "unquenchable, inextinguishable", of fire, Il. ; of laughter, etc., Hom. ; ἄσβ. πόρος ὠκεανοῦ ocean's "ceaseless" flow, Aesch. as Subst., ἄσβεστος (sc. τίτανος), "unslaked lime", Plut.
STEPBible — Tyndale Abridged Greek Lexicon
ἄ-σβεστος, -ον
(σβέννυμι), [in LXX for נָפַח לֹא, Job.20:26 א3 A (ἄκαυστον, א2 B)* ;]
unquenched, unquenchable: πῦρ, Mat.3:12, Mrk.9:43, Luk.3:17.†
(AS)