Lexical Definition

‎λανθάνω‎ lanthánō (lan-than'-o) be hidden ^G:V
a prolonged form of a primary verb, which is used only as an alternate in certain tenses

be hid, be ignorant of, unawares.

• to lie hid (literally or figuratively)
• often used adverbially, unwittingly

Abbott-Smith

λανθάνω, [in LXX for עלם ni., etc.;]
to escape notice, be hidden (from): Mk 7:24, Lk 8:47; c. acc. pers., Ac 26:26, II Pe 3:5, 8; as in common cl. idiom, seq. ptcp., ἔλαθον ξενίσαντες, entertained unawares, He 13:2 (cf. ἐκ-, ἐπι-λανθάνω).†

Abbott-Smith References

Liddell-Scott-Jones

λανθάνω,

[Refs 5th c.BC+]:—also λήθω (which is the form of the active generally used in compounds, δια-λανθάνω being the sole exception), [Refs 8th c.BC+]; Doric dialect λάθω [ᾱ] [Refs 5th c.BC+]; infinitive

__A λᾱθέμεν [Refs 5th c.BC+]: imperfect ἐλάνθανον [Refs 8th c.BC+]; Epic dialect λῆθον [Refs 8th c.BC+]; Ionic dialect λήθεσκεν [Refs]: future λήσω [Refs 8th c.BC+]; Aeolic dialect infinitive λᾱσην [Refs 7th c.BC+]; Doric dialect λᾱσῶ [Refs 3rd c.BC+]: aorist 1 ἔλησα [Refs 8th c.BC+]: aorist 2 ἔλᾰθον [Refs 8th c.BC+]: perfect λέληθα [Refs 7th c.BC+]; Aeolic dialect participle λελᾱθων [Refs 7th c.BC+]pluperfect ἐλελήθειν, Attic dialect -ήθη, [Refs 5th c.BC+]; Ionic dialect3rd.pers. singular ἐλελήθεε [Refs 5th c.BC+]
__B causal ληθάνω, aorist 2 λέλᾰθον, see below [Refs 5th c.BC+]
__C middle and passive, λανθάνομαι [Refs 8th c.BC+]; Doric dialect λάθομαι [ᾱ] [Refs 5th c.BC+]: Epic dialect imperfect λανθανόμην [Refs 8th c.BC+]: future λήσομαι [Refs]; Doric dialect λᾱσεῦμαι [Refs 5th c.BC+]aorist 1 ἐλησάμην or λησάμην only in late Epic dialect, [Refs 3rd c.BC+] (Doric dialect λᾱς-), [Refs 4th c.AD+]; also ἐλήσθην, Doric dialect infinitive λασθῆμεν [λανθάνω: ">Refs 3rd c.BC+]aorist 2 ἐλᾰθόμην, Epic dialect λαθ-, [Refs 8th c.BC+]: rare in Prose except in compounds, [Refs 1st c.AD+]; also Epic dialect reduplicate λελάθοντο, etc., see below c: perfect λέλησμαι [Refs 5th c.BC+]; Epic dialect λέλασμαι, participle λελασμένος, etc.; compare ἐπιλήθω.
__A in most of the active tenses, escape notice (frequently joined with a negative):—Constr.:
__A.1 with accusative person only, escape his notice, λάθε δ᾽ Ἕκτορα [Refs 8th c.BC+]; εἰ λανθάνει σε perhaps you don't know, [Refs 4th c.BC+] it escaped the notice of the people, [Refs 5th c.BC+]; σὲ δὲ λέληθεν περὶ τοῦτο ὡς.. [Refs 5th c.BC+]
__A.2 most frequently with a participle added, in which case we usually translate the participle by a Verb, and express λανθάνω by an adverb, unawares, without being observed; either,
__A.2.a with accusative person, ἄλλον τινὰ λήθω μαρνάμενος I am unseen by others while fighting, i.e. [Refs]unseen by them, [Refs 8th c.BC+] lest he come on unseen by me, [Refs 5th c.BC+]; ὅπως μὴ λήσουσιν αὐτοὺς αἱ νῆες.. ἀφορμηθεῖσαι should put to sea without their observing them, [Refs 5th c.BC+]; or,
__A.2.b without an accusative, φονέα ἐλάνθανε βόσκων he maintained the murderer unawares, [Refs 5th c.BC+]: the reflexive pronoun may be supplied and is sometimes added, λέληθεν αὑτὸν τοῖς ξυνοῦσιν ὢν βαρύς [Refs 8th c.BC+]; μὴ διαφθαρεὶς λάθῃ [τινὰ ὁ βίος] [Refs 5th c.BC+] —In a few examples this _construction_ is reversed, and λαθών is put in the participle, as in our idiom, ἀπὸ τείχεος ἆλτο λαθών (for ἔλαθεν ἁλόμενος) [Refs 8th c.BC+]
__A.3 rarely with accusative et infinitive, μή σε λαθέτω ὑπερτιθέμεν let it not escape thee to.., i.e. forget not to.., [Refs 5th c.BC+]; σφᾶς λέληθε Θεόδωρον εἶναι it has been unnoticed that it was.., [Refs 2nd c.AD+]
__A.4 followed by a relative clause, οὐδέ με λήθεις, ὅττι θεῶν τίς σ᾽ ἦγε thou escapest me not, it is not unknown to me, that some god led thee, [Refs 8th c.BC+]; ἐδόκεες θεοὺς λήσειν οἷα ἐμηχανῶ thou thought'st to escape the gods' notice in.., [Refs 5th c.BC+]; οὐ λανθάνεις με, ὅτι.. [Refs 5th c.BC+]; ὁ γείτων λ. τινὰ οὐ μόνον ὅτι πράττει, ἀλλ᾽ εἰ.. [Refs 5th c.BC+]
__A.5 absolutely, escape notice or detection, [Refs 5th c.BC+]
__B causal, make one forget a thing, with genitive of things, in compounds ἐκληθάνω, ἐπι-λήθ; the simple Verb only in Epic dialect reduplicate aorist 2, ὄφρα.. λελάθῃ ὀδυνάων that.. he may cause him to forget his pains, [Refs 8th c.BC+]
__B.II in late Epic dialect, λέλαθον, ={ἔλαθον}, escaped notice of, ἑὸν νόον, τοκῆας, [Refs 3rd c.BC+]
__C middle and passive, let a thing escape one, forget,
__C.1 forget simply, in present (absolutely), σὺ δὲ λήθεαι [Refs 8th c.BC+]: mostly in aorist 2, ἀλκῆς λαθέσθαι [Refs 8th c.BC+]: also in reduplicate aorist, οὐδὲ σέθεν.. θεοὶ μάκαρες λελάθοντο [Refs 8th c.BC+] that she might bear unknown): so in perfect, τῶν δὲ λέλασται [Refs 8th c.BC+]: with a relative clause, λελασμένος ὅσσ᾽ ἐπεπόνθει [Refs 8th c.BC+]: future middle in passive sense, once in [Refs 5th c.BC+] never will be forgotten, El.1249 (Lyric poetry); compare ἐπιλανθάνω.
__C.2 forget purposely, pass over, ἢ λάθετ᾽ ἢ οὐκ ἐνόησεν either he chose to forget it.., [Refs 8th c.BC+]
__C.II in later writers future middle is used like active, escape notice, ἡμᾶς [Refs 4th c.BC+]