Quick Definition
ἀμετάθετος, ον Adj unchanged, unchangeable
Strong's Definition
from 1 (as a negative particle) and a derivative of 3346; unchangeable, or (neuter as abstract) unchangeability
KJV Usage: immutable(-ility)
UBS Dictionary of the Greek New Testament
UBS Dictionary of the Greek New Testament © United Bible Societies, licensed CC BY-SA 4.0.
Thayer's Greek Lexicon
ἀ-μετάθετος, -ov, (μετατίθημι), not transposed, not to be transferred ; fixed, unalterable: Heb. vi. 18; τὸ ἀμετάθεtov as subst., immutability, Heb. vi.17. (8 Mace. v. 1; Polyb., Diod., Plut.)
Mounce Concise Greek Dictionary
ἀμετάθετος ametathetos 2x
unchangeable, Heb. 6:17, 18*
Abbott-Smith Greek Lexicon
*† ἀ-μετάθετος, -ον
(< μετατίθημι), [in LXX: III Mac 5:1,12*;]
immutable: He 6:18; as subst., τὸ ἀ., immutability, He 6:17 (v. MM, VGT, s.v.).†
Moulton & Milligan — Vocabulary of the Greek NT
ἀμετάθετος. In OG/S 331° (ii/B.c.) King Attalus II of Pergamon, writing to the Pergamenes, orders his rescript to be placed in the temples, ὅπως ἂν εἰς τὸν ἅπαντα χρόνον ἀκίνητα καὶ ἀμετάθετα μένηι : cf. 25. 3357 (an Aeolic inscription, ii/i B.c.) [τὰ δὲ κρίθεντα ὑ]π[ά)ρξοισι κύρια καὶ ἀμετάθετα. A letter from Sulenas Verus in Lafoscade, no. 10511 (A.D. 131) has βεβαιῶ ἐπί τε τῷ ἀσάλευτον [sc. τὴν δωρεὰν] Kal ἀμετάθετον εἰς τὸν ἀεὶ χρόνον εἶναι καὶ κτλ. P Oxy Ι. 751" (A.D. 129) ἐφ᾽ ἡ Loe. διαθήκῃ] ἀμεταθέτῳ ἀμφότεροι ἐτελεύτησαν, and zd. IIT. 4825 (A.D. 109) διαθήκῃ, ἐφ᾽ ἢ καὶ ἀμεταθέτῳ ἐτελεύτα (‘which will was unchanged at his death”’), show that the word was used as a technical term in connexion with wills. The connotation adds considerably to the force of Heb 617%.
Liddell-Scott-Jones — Greek-English Lexicon
ἀμετάθετος (ametathetos) — unchangeable. ἀμετά-θετος, ον, unalterable, immutable, κατάληψις, of knowledge, [Refs 4th c.BC+]; of fate, Chrysipp.[Refs 2nd c.BC+], etc. adverb -τως, διακεῖσθαι[Refs 1st c.BC+]
2. Grammars, not inflected, [Refs 2nd c.AD+]