G1964
ἐπιορκέω
to break an oath
ἐπιορκέω, -ῶ (ἐπίορκος), [in LXX: I Est.1:48, Wis.14:28 * ;] to swear falsely, forswear oneself: Mat.5:33.† (AS)
The KJV translates G1964 in the following manner:
shalt (2x), thyself (2x)
Full Thayer's lexicon entry
ἐπιορκέω — epiorkéō
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.)
1 occurrence