Quick Definition
I take an oath, swear falsely
Strong's Definition
to commit perjury
Derivation: from G1965 (ἐπίορκος);
KJV Usage: forswear self
Thayer's Greek Lexicon
ἐπιορκέω, ἐπιόρκω: future ἐπιορκήσω, cf. Krüger, § 40, under the word, and § 39, 12, 4; (Veitch, under the word; Buttmann, 53 (46)); (ἐπίορκος, which see); to swear falsely, forswear oneself: Mat_5:33. (Wis_14:28; 1Es_1:46; by Greek writings from Homer down.)
Mounce Concise Greek Dictionary
ἐπιορκέω epiorkeō 1x
to forswear one s self, to fail of observing one s oath, Mat_5:33
Abbott-Smith Greek Lexicon
** ἐπιορκέω , -ῶ
( < ἐπίορκος ),
[in LXX : 1Es_1:48 , Wis_14:28 * ;]
to swear falsely, forswear oneself: Mat_5:33 .†
Moulton & Milligan — Vocabulary of the Greek NT
ἐπιορκέω / ἐφιορκέω [page 242]
The aspirated form, banned by WH as Western, and explained by Thumb ( Spiritus asper , p. 72) as due to a contamination of ἐφορκέω and ἐπιορκέω , is common in papyri and inscrr. in the legal formula εὐορκοῦντι μέν μοι εὖ εἴη , ἐφιορκοῦντι δὲ τὰ ἐναντία , if my oath is kept, may it be well with me, but if false, the reverse : e.g. P Tebt I. 78 .17 (B.C. 110 8), P Oxy II. 253 .23 (A.D. 19), ib. 255 .24 (A.D. 48), OGIS 229 .69 (iii/B.C.). See also Moulton Gr. ii.
Liddell-Scott — Intermediate Greek Lexicon
ἐπιορκέω fut. ήσω aor1 -ώρκησα perf. -ώρκηκα [Etym: from ἐπίορκος] "to swear falsely, forswear oneself", πρὸς δαίμονος "by" a deity, Il. ; c. acc., τοὺς θεούς "by" the gods, Ar. , Xen.
STEPBible — Tyndale Abridged Greek Lexicon
ἐπιορκέω, -ῶ
(ἐπίορκος), [in LXX: I Est.1:48, Wis.14:28 * ;]
to swear falsely, forswear oneself: Mat.5:33.†
(AS)