Quick Definition
secretly
Strong's Definition
privately
Derivation: adverb from G2990 (λανθάνω);
KJV Usage: privily, secretly
Thayer's Greek Lexicon
λάθρᾳ (so R G T Tr) (in Homer λάθρῃ, from λανθάνω, λαθεῖν), and L (WH K C (see the latter's Praef., p. 12: and under the word εἰκῇ)) λάθρᾳ (from λαθρος, λάθρᾳ, λαθρον, cf. Passow (especially Liddell and Scott), under the word; Winers Grammar, 47; Buttmann, 69 (61)), adverb secretly: Mat_1:19; Mat_2:7; Joh_11:28; Act_16:37. (From Homer down; the Sept..)
Mounce Concise Greek Dictionary
λάθρᾳ lathrai 4x
secretly, privately, Mat_1:19 ; Mat_2:7 ; Joh_11:28 ; Act_16:37
Abbott-Smith Greek Lexicon
λάθρᾳ
( Att. .; in Hom ., -ρῃ , Rec. -ρα ),
adv. ,
[in LXX chiefly for H5643 ;]
secretly: Mat_1:19 ; Mat_2:7 , Mar_5:33 ( WH , mg .), Joh_11:28 , Act_16:37 .†
Moulton & Milligan — Vocabulary of the Greek NT
λάθρα [page 368]
λάθρα , which Moulton ( Gr. ii. p. 84) prefers to write instead of λάθρᾳ , occurs in P Par 22 .28 (B.C. 165) τοῦτον ( sc. λίνον ) λάθρα κομισάμενος : cf. BGU IV. 1141 .48 (B.C. 14). See also Boisacq (p. 549) who treats the form as an instrumental singular.
STEPBible — Tyndale Abridged Greek Lexicon
λάθρᾳ (Att..; in Hom., -ρῃ, Rec. -ρα),
adv., [in LXX chiefly for סֵתֶר ;]
secretly: Mat.1:19 2:7, Mrk.5:33 (WH, mg.), Jhn.11:28, Act.16:37.†
(AS)