Lexical Definition

‎πάλαι‎ pálai (pal'-ahee) of old G:ADV
probably another form for ‎πάλιν‎ (through the idea of retrocession)

any while, a great while ago, (of) old, in time past.

Usage: 1 form in 10 verses
Form Translated As     In Verse(s)
πάλαι Previously 2Cor.12.19
earlier LXX.Isa.37.26LXX.Isa.48.5LXX.Isa.48.7
former 2Pet.1.9
long ago Matt.11.21Luke.10.13Heb.1.1Jude.1.4
of old Mark.15.44

Abbott-Smith

πάλαι, adv. of time, [in LXX: Is 48:5, 7 (מֵאָז), etc.;]
long ago, of old, in time past (denoting past time absolutely, as πρότερον relatively): Mt 11:21, Lk 10:13, He 1:1, Ju 4; as adj., c. art., II Pe 1:9; of time just past, Mk 6:47 (WH, mg.), 15:44 (WH, mg., R, txt.); c. durat. praes. (RV, all this time), II Co 12:19.†

Abbott-Smith References

Book Refs
Isaiah 48:5 · 48:7
Matthew 11:21
Mark 6:47 · 15:44
Luke 10:13
2 Corinthians 12:19
Hebrews 1:1
2 Peter 1:9
Jude 1:4

Liddell-Scott-Jones

πάλαι [],

adverb long ago, π. οὔ τι νέον γε [Refs 8th c.BC+]; π. ποτέ once upon a time, [Refs 5th c.BC+]present of an act lasting to the present, ὁρῶ.. π. I have long seen, [Refs 5th c.BC+]; ἰχνεύω π.[Refs 5th c.BC+]; but, π. ποτ᾽ ὄντες ye who were long ago, [Refs]: also with perfect, τέθνηχ᾽ ὑμῖν π. [Refs 5th c.BC+]imperfect of an act lasting to a past time, ἔχεν π. had long been holding it, [Refs 8th c.BC+]

__2 like an adjective with Article and Noun, οἱ π. φῶτες men of old, [Refs 5th c.BC+]; τὰ καινὰ τοῖς π. τεκμαίρεται[Refs 4th c.BC+]; οἱ π. the ancients, opposed to οἱ νῦν, [Refs 4th c.BC+]
__II before, opposed to the present, sometimes of time just past, ἠμὲν π. ἠδ᾽ ἔτι καὶ νῦν [Refs 8th c.BC+]: hence, not long ago, just now, like{ἄρτι}, οἱ π. λόγοι [Refs 4th c.BC+]; π. λόγος the reason just given, [Refs 5th c.BC+]; but opposed to ἄρτι, [Refs 5th c.BC+]