Lexical Definition

‎σπουδαῖος‎ spoudaîos (spoo-dah'-yos) eager ^G:A
from ‎σπουδή‎

diligent.

• prompt, energetic, earnest

Abbott-Smith

σπουδαῖος, -α, -ον (< σπουδή), [in LXX: Ez 41:25 * ;]
in haste; hence, zealous, eager, diligent, earnest: seq. ἐν, II Co 8:22; compar., -οτεροσς ib. 17 (here in superl. sense, v. Bl., § 44, 3) 22.†

Abbott-Smith References

Liddell-Scott-Jones

σπουδαῖος-αῖος, α, ον

(σπουδαῖοςή) properly in haste, quick, σ. τοὺς πόδας [Refs 2nd c.AD+]:—but in ordinary use denoting energy or earnestness:

__I of persons, earnest, serious, [Refs 5th c.BC+]; active, zealous, in canvassing, [Refs 1st c.AD+]
__I.2 good, excellent in their several kinds, [Refs 5th c.BC+]; opposed to φαῦλος, [Refs 5th c.BC+]; ἀκροαταὶ-ότεροι [Refs 5th c.BC+]; σ. αὐλητής, opposed to ἄνθρωπος μοχθηρός, [Refs 5th c.BC+]
__I.3 in moral sense, good, opposed to πονηρός, [Refs 5th c.BC+]; opposed to φαῦλος, [Refs 5th c.BC+]; σπουδαῖοςαῖον ={ἀγαθον}, [Refs]: generally, of all virtuous objects or qualities, [Refs]
__II of things, worth serious attention, weighty, χρῆμα, πρῆγμα, [Refs 6th c.BC+]; τὰ -έστερα (-έστατα) τῶν πρηγμάτων [σπουδαῖοςαιότατ᾽ ἐστίν 4th c.BC: Demosthenes Orator 24.4 ">Refs 5th c.BC+]; opposed to γελοῖος, [Refs 5th c.BC+]; τί γελᾷς ἐπὶ σπουδαῖοςαίοις πράγμασι; [Refs 5th c.BC+]
__II.2 good of its kind, excellent, σ. νομαί [Refs 5th c.BC+]; ἡ σπουδαῖοςαιοτάτη [τῶν ταριχεύσεων] the most elaborate, costliest, [Refs 3rd c.BC+]; ἡ ἰσηγορίη χρῆμα σ. [Refs 5th c.BC+]; λόγος σ. [Refs 5th c.BC+]; δῶρον οὐ σ. εἰς ὄψιν not goodly to look on, [Refs 5th c.BC+]; τραγῳδία σ. [Refs 4th c.BC+]:— a play on senses [Refs 4th c.BC+]; ironically, σ. χρῆμα a fine thing, [Refs]
__III adverb σπουδαῖοςαίως with haste or zeal, seriously, earnestly, well, [Refs 5th c.BC+]: comparative -ότερον[Refs 5th c.BC+]; -οτέρως [Refs 1st c.AD+] most carefully, in the best way, [Refs 5th c.BC+]