Quick Definition
I speak aloud, utter
Strong's Definition
to utter a clear sound, i.e. (generally) to proclaim
Derivation: probably akin to G5338 (φέγγος) and thus to G5346 (φημί);
KJV Usage: speak
Thayer's Greek Lexicon
φθέγγομαι; 1 aorist participle φθεγξάμενος; (φέγγος (but cf. Vanicek, p. 1176), ΦΑΩ); deponent middle; from Homer down;
1. to give out a sound, noise, or cry; used by the Greeks of any sort of sound or voice, whether of man or animal or inanimate object as of thunder, musical instruments, etc.; (φθέγγεσθαι denotes sound in its relation to the hearer rather than to its cause; the μέγα λαλῶν is a braggart, the μέγα φθεγγόμενος. is a lofty orator; Schmidt, Syn., chapter 1 § 53).
2. to proclaim; to speak, utter: Act_4:18; ὑπέρογκα, 2Pe_2:18 (ἄδικα, Wis_1:8); ὑποζύγιον, ἄφωνον ἐν ἀνθρωπίνῃ φωνή φθεγξάμενον, 2Pe_2:16. (Compare: ἀποφθέγγομαι.)
Mounce Concise Greek Dictionary
φθέγγομαι phthengomai 3x
to emit a sound; to speak, Act_4:18 ; 2Pe_2:16 ; 2Pe_2:18
Abbott-Smith Greek Lexicon
φθέγγομαι ,
[in LXX for H6030 , H5042 hi ., etc.;]
of men or animals, to utte r a sound or voice: absol. , Act_4:18 ; seq . ἐν φωνῇ , 2Pe_2:16 ; c . acc , ὑπέρογκα , 2Pe_2:18 .†
Moulton & Milligan — Vocabulary of the Greek NT
φθέλλομαι [page 667]
utter c. ace. as in 2Pe. 2:18 : cf. P Leid W xix. 10 (ii/iii A.D.) (= II. p. 147) ἐπικλοῦμαί σε . . . οὖ τὸ ὄνομα οὐδέ θεοὶ δύναται ( l. δύνανται ) φθέγγεσθαι . For the absol. use of the verb, as in Act. 4:18, see the epigram PSI I. 17 iv. .1f. (iii/A.D.?)
Ει᾽ καὶ τὴν φωνὴν ὁ ζῳγράφος ὧδ᾽ ἐνέθηκεν ,
εἶπες ἂν ὡς ἤδη φθέγγεται Εὐπέπιος .
The reference is to abusive language in P Lond 983 .13 (iv/A.D.) (=111. p. 229), a petition that a certain woman should he called to account ὧν καθ᾽ ἡμῶν ἐφθέγξατο , similarly P Flor III. 309 .11 (iv/A.D.), and from the inscrr. Syll 809 (= .3 1175) .6 (iv/iii B.C.) ῥῆμα μοχθηρὸν φθένγεσθαι .
Liddell-Scott — Intermediate Greek Lexicon
φθέγγομαι "to utter a sound or voice", esp. "to speak loud and clear, speak", Hom. , etc. of animals, as a horse, "to neigh, whinny", Hdt. ; of an eagle, "to scream", Xen. ; of a fawn, "to cry", Theocr. of inanimate things, of a door, "to creak", Ar. ; of thunder, "to sound", Xen. ; of musical instruments, Il. = ὀνομάζω, "to name, call by name", Plat. c. acc. pers. "to celebrate" one "aloud, extol", Pind.
STEPBible — Tyndale Abridged Greek Lexicon
φθέγγομαι
[in LXX for עָנָה, נָבַע hi., etc. ;]
of men or animals, to utter a sound or voice: absol., Act.4:18; before ἐν φωνῇ, 2Pe.2:16; with accusative, ὑπέρογκα, 2Pe.2:18.†
(AS)