Quick Definition
φύλαξ, ακός, ὁ n.m. a guard, keeper, sentinel
Strong's Definition
from 5442; a watcher or sentry
KJV Usage: keeper
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
Φύλαξ, -axos, ὁ, (φυλάσσω), a guard, keeper: Acts v. 23; xii. 6,19. (From Hom. down; Sept. for 7¥7.)
Mounce Concise Greek Dictionary
φύλαξ phylax 3x
a watchman, guard, sentinel, Acts 5:23; 12:6, 19*
Abbott-Smith Greek Lexicon
φύλαξ, -ακος, ὁ
(< φυλάσσω), [in LXX for שָׁמַר, צוּר ;]
a guard, keeper: Ac 5:23 12:6, 19.†
Moulton & Milligan — Vocabulary of the Greek NT
φύλαξ, “a guard”: P Hib I. 147 (early iii/B.c.) σύντασσε [τοὺς] παρὰ col φίύλακας φυλάσσειν καὶ προ σ]έχειν ἵνα κτλ., P Oxy II. 803 (late i/B.c.) τοὺς ἀπὸ τοῦ νομοῦ φύλακας, BGU III. 83034 (i/A.p.) τοὺς φιλακες (1 φύλακας) ἡμῶν σκῦλον πρὸς αὐ[τ]ήν, 70. 7291! (A.D. 137) ὃν δὲ ἐὰν βούληται ὁ Σαραπίων ὀπωροφύλακα φυλάσσιφν» τῷ τῆς ὀπώρας καιρῷ φύλακα πέμψει, ‘ Sarapion shall send any guard whom he chooses in order to protect the fruit at the time of bearing” (Edd.), and 26. VI. 9318 (ii/A.pD.) ἔπεμψα διὰ τοῦ κομίσαντος [τ]ὸ ἀπὸ σοῦ ἐπιστόλιον φύλακος... “1 have sent by the guard who brought the letter from you . . .” For the different orders of φύλακες see Jouguet Vze Municipale, p. 261 ff., and for φύλακτρον, ““ police-tax,”’ see P Oxy III. 50248 (A.D. 164) with the editors’ note.
Liddell-Scott-Jones — Greek-English Lexicon
φυλακτήριος (phulaktērios) — guard. φῠλᾰκ-τήριος, α, ον, serving as a protection, τὰ περί τι φ. [Refs 5th c.BC+], φῠλᾰκ-της, ου, ὁ, one who preserves, τῶν ἰδίων ἐθῶν [Refs 1st c.AD+]
II. ={φυλακτήρ}, a magistrate at Cumae, [Refs 1st c.AD+]