ἅπαξ [ᾰπ],
adverb once, once only, once for all, first in [[ 8th c.BC: Odyssea Homerus Epicus “Odyssey”, ὅτε τ᾽ ἄλλοι ἅ. θνῄσκουσ᾽ ἄνθρωποι 12.22] Refs 8th c.BC+]; ἅ... ἀπὸ θυμὸν ὀλέσσαι[[ [prev. work] 350; ἀπαλλάχθηθ᾽ ἅ. 5th c.BC: Euripides Tragicus “Cyclops” 600] Refs 5th c.BC+]; οὐχ ἅ. μόνον more than once, [[ 4th-5th c.BC: Aeschylus Tragicus “Prometheus Vinctus” 211; ἅ... κοὐχὶ δίς 5th c.BC: Sophocles Tragicus “Oedipus Coloneus” 1208; πολλάκις καὶ οὐχὶ ἅ. 5th c.BC: Herodotus Historicus 7.46; πολλάκις τε κοὐχ ἅ. 5th c.BC: Sophocles Tragicus “Oedipus Tyrannus” 1275; μὴ ἅ. ἀλλὰ πολλάκις 5th c.BC: Antipho Orator 1.3, compare 5th-6th c.BC: Plato Philosophus “Leges” 711a; μὴ δίς, ἀλλ᾽ ἅ. μόνον 4th c.BC: Aristoteles Philosophus “Politica” 1299a10 ] Refs 5th c.BC+]; of the self-creation of Νοῦς, τὴν ποίησιν αὑτοῦ.. ἅ. εἶναι[[ 3rd c.AD: Plotinus Philosophus 6.8.21] Refs 3rd c.AD+]; ἅ. ἔτι yet this once, [[ 4th-5th c.BC: Aeschylus Tragicus “Agamemnon” 1322] Refs 4th c.BC+]; τὸ ἅ. τοῦτο at this moment, [[ LXX.2Ki.17.7] LXX]; ἅ. δυοῖν ποδοῖν, i.e. two square feet [[(1 x 2), opposed to δυοῖν δίς (2 x 2), ] Refs]four, [[ 5th-6th c.BC: Plato Philosophus “Meno” 82c. ] Refs 5th c.BC+]
__2 with genitive, ἅ. τοῦ ἐνιαυτοῦ, ἔτεος ἑκάστου ἅ., [[ 5th c.BC: Herodotus Historicus 2.59, 4.105; also ἐν τῷ ἐνιαυτῷ ἅ. [prev. author] 2.132. ] Refs 5th c.BC+]
__3 once on a time, formerly, ἅ. καὶ ἅ.[[ LXX.Judg.20.30. ] LXX]
__II without any notion of number, after conditional and temporal Particles, if once, when once, εἴπερ ἐσπείσω γ᾽ ἅ. if once you have made a treaty, [[ 5th-6th c.BC: Aristophanes Comicus “Acharnenses” 307. compare 923; ἢν ἅ. ἁλῷ [prev. author] “V.” 898, compare “Av.” 342; ἂν ἅ. τις ἀποθάνῃ 4th c.BC: Amphis Comicus 8; ἐπειδήπερ γ᾽ ἅ. ἐμοὶ σεαυτὸν παραδέδωκας 5th-6th c.BC: Aristophanes Comicus “Vespae” 1129; ἐπεὶ ἅ. ἐταράχθησαν 5th c.BC: Thucydides Historicus 7.44; ὡς ἅ. ἤρξατο 5th-6th c.BC: Xenophon Historicus “Historia Graeca (Hellenica)” 5.4.58; ἐπεὶ ἅ. αὐτοῖς φίλος ἐγένετο [prev. author] “An.” 1.9.10, compare 3.2.25, 5th-6th c.BC: Isocrates Orator 12.242; ὡς ἅ. ἐγκλήματα ἐταράχθη 4th c.BC: Demosthenes Orator 18.151] Refs 5th c.BC+]: so with participle, ἐπὶ γᾶν ἅ. πεσὸν... αἷμα[[ 4th-5th c.BC: Aeschylus Tragicus “Agamemnon” 1019(Lyric poetry); ἅ. θανόντος οὔτις ἔστ᾽ ἀνάστασις [prev. author] “Eu.” 648; ἅ. ἐλθόντες 5th-6th c.BC: Plato Philosophus “Parmenides” 165e, cf. NT.Heb.6.4, etc. (ἁ-] NT+5th c.BC+] = sṃ (compare εἷς); -παξ akin to πήγνυμι.)