LSJ
(sc. ἡμέρα), ἡ, day appointed beforehand, a fixed or limited time, within which money was to be paid, actions brought, claims made, elections held, etc., and if this period was allowed to expire, no further proceedings were allowed, D. 36.25, Aeschin. 1.39; ἐὰν ἡ π. ἐξήκῃ is past, IG1². 41.9; τριετὴς π. Pl. Lg. 954d, cf. D. 38.27, Paus. 4.5.10. generally, fixed or appointed time, προθεσμίας οὔσης τῷ κινδύνῳ Lys. 7.17; π. ἀδικημάτων Id. 13.83; μηδεμίαν εἶναι π. τῆς ἐπιλήψεως Pl. Lg. 954e; τῆς προθεσμίας ὀλίγης εἰς τὴν χειροτονίαν οὔσης App. BC 1.14, cf. Ep. Gal. 4.2, OGI 509.21 (Aphrodisias, ii AD); οὐκ ἐτήρησε τὴν π. τῆς θεοῦ Supp.Epigr. 4.649 (Lydia, ii AD); π. φυσικὴ [νόσου] natural period, Gal. 1.289; ἡ π. τῆς καθάρσεως Sor. 2.10, cf. 1.21, al. ; pl., τρεῖς τοῦ μηνὸς ἀρχαὶ καὶ π. (Kalends, Nones and Ides) Plu. 2.269b; προθεσμίας ὁριζομένους ἑορτάς Luc. Nigr. 27.
occasion of delay, J. AJ 15.55.1. προθέσμιος, α, ον, Adj. foreappointed, Ἔφεσος, ἡ π. τῶν γάμων (sc. πόλις) Ach.Tat. 5.21.
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)
TBESG
προ-θέσμιος, -α, -ον
[in Sm.: Job.28:3, Dan.9:26 * ;]
appointed beforehand. In Attic law, as subst. (so always in cl.), ἡ π. (sc. ἡμέρα), a day appointed beforehand, a previously appointed time: Gal.4:2.†
(AS)
Translators Brief lexicon of Extended Strongs for Greek based on Abbot-Smith, A Manual Greek Lexicon of the New Testament (1922) (=AS), with corrections and adapted by Tyndale Scholars