εἴπερ
or εἴ περ, strengthened for εἰ, if really, if indeed, [[ 8th c.BC: Ilias Homerus Epicus “Illiad” 3.25, etc.] Refs 8th c.BC+]; especially even if, even though, [[ 8th c.BC: Ilias Homerus Epicus “Illiad” 7.117, 8th c.BC: Odyssea Homerus Epicus “Odyssey” 1.167, etc.; εἴ. καί 9.35; εἴ. τε 8th c.BC: Ilias Homerus Epicus “Illiad” 10.225; εἴ. γε 4th-5th c.BC: Aeschylus Tragicus “Choephori” 198, 5th-6th c.BC: Plato Philosophus “Protagoras” 312a, etc.; εἴ. γε δή [prev. author] “Tht.” 182c ] Refs 8th c.BC+]; with words between, εἴ. γάρ τε χόλον γε.. [[ 8th c.BC: Ilias Homerus Epicus “Illiad” 1.81; εἴπερ ἔσται γε 4th-5th c.BC: Aeschylus Tragicus “Agamemnon” 1249, compare 5th-6th c.BC: Plato Philosophus “Politicus” 275e; καλῶς, εἴπερ ποτέ, ἔχει 5th c.BC: Thucydides Historicus 4.20; εἴπερ ἄρα 4th c.AD: Julianus Imperator “Orationes” 7.216b. ] Refs 8th c.BC+]
__II in Attic dialect and Trag. to imply that the supposition agrees with the fact, if as is the fact, since, [[ 5th c.BC: Thucydides Historicus 6.14, etc.] Refs 5th c.BC+]; but with imperfect it implies that it is contrary to the fact, εἴπερ ἦν πέλας if I had been (but I was not), [[ 5th c.BC: Sophocles Tragicus “Electra” 312, compare 604 ] Refs 5th c.BC+]; also εἴ. ἐκτελεῖς ἅπερ λέγεις if only you will keep your word, [[ [prev. author] “Ichn.” 48. ] Refs]
__III with an ellipse, if you must, [[ 5th-6th c.BC: Aristophanes Comicus “Nubes” 227 ] Refs 5th c.BC+]; ἀλλ᾽ εἴ. but if so, [[ 5th-6th c.BC: Plato Philosophus “Parmenides” 150b, 4th c.BC: Aristoteles Philosophus “Ethica Nicomachea” 1101a12; compare εἰ 5th c.BC: Bacchylides Lyricus VII. ] Refs 5th c.BC+]