Quick Definition
νεανίας, ου, ὁ n.m. a young man, youth
Strong's Definition
from a derivative of 3501; a youth (up to about forty years)
KJV Usage: young man
UBS Dictionary of the Greek New Testament
noun, m. | -ου | νέος
9.32 · People · Males
young man a young man beyond the age of puberty, but normally before marriage The person referred to as a νεανίας in ACT 20:9 is called a παῖς ‘boy’ (see 9.41) in ACT 20:12. This should not be understood as identity in meaning, since the person concerned could have been of such an age that either ‘young man’ or ‘boy’ was a possible denotation. In other words, the age reference of νεανίας and παῖς overlaps in Greek. In a number of languages, however, there is a much more specific and clear-cut distinction in age grading.
UBS Dictionary of the Greek New Testament © United Bible Societies, licensed CC BY-SA 4.0.
Thayer's Greek Lexicon
νεανίας, -ov, 6, (fr. vedv, and this fr. véos; cf. μεγιστάν [q- v-], ξυνάν), fr. Hom. down; Hebr. 3y1) and 73n3; a young man: Acts xx. 9; xxiii. 17, and RG in 18 [so here WH tzxt.], 22; it is used asin Grk. writ., like the Lat. adulescens and the Hebr. Ἢ} (Gen. xli. 12), of men between twenty-four and forty years of age [οἵ. Lob. ad Phryn. p. 213; Diog. Laért. 8,10; other reff. in Steph. Thesaur. 8. VV. νεᾶνις, νεανίσκος]: Acts vii. 58.
Mounce Concise Greek Dictionary
νεανίας neanias 3x
a young man, youth, Acts 20:9; 23:17; used of one who is in the prime of life, Acts 7:58*
Abbott-Smith Greek Lexicon
νεανίας, -ου, ὁ
(< νεάν = νέος), [in LXX for נַעַר, בָּחוּר;]
a young man: Ac 7:58 20:9 23:17, 18.†
Moulton & Milligan — Vocabulary of the Greek NT
νεανίας is restored in P Oxy IIT. 4714 (ii/a.p.) with reference to a boy of seventeen who had not been sent—émt ra] διδαokad¢tja κα[ὶ] τ[ὰς προ]σηκούσας τοῖς ν[ εανί]α[ις] τριβ[ά!ς, “εἴο the schools and the exercises proper for the young ”’ (Edd.): cf. νὴ 425 (=*%546B)?> (p.c. 216-14) εἰς τὸ ἔλαιον τοῖς veaviors (/. -αις) στατῆρας δέκα. For νεανιevopat of acting with youthful recklessness see P Grenf II. 78° (A.D. 307). The word is derived from a hypothetical abstract noun *veFa, ‘‘ youth” (Boisacq, p. 659). veaviaxoc. In P Amh II. 39? (late ii/B.c.) the members of a chosen band of youths are described as—ot [ἐκ] τοῦ σημείου veaνίσκοι. Cf. also for the word P Par 60 dys! (c. B.c. 200) ὥστίε φυλάττειν καὶ καταστῆσαι] τοὺς νεανίσκους, P Oxy III. 53328 (ii/iii A.D.) where directions are given not to lease a house—veaviokots ἵϊν]α μὴ ἔχωμεν στομάχους9] μηδὲ φθόνον, ‘‘to youths that we may not be caused vexation and annoyance” (Edd.), and from the inscrr. Sy// 802 (ΞΞ 1168) 115 (c. B.C. 320) νεανίσκον εὐπρεπῆ τὰμ μορφάν, OGIS 443° (i/B.c.) τήν τε τῶν [ὑποτεταγμένων] ἑαυτῶι νεανίσκων ἐνδημίαν εὔτίακτ]ον παρέχεται καὶ ἄμεμπτον. The dim. νεανισκάριον occurs in Epict. ii. 16. 29.
Liddell-Scott-Jones — Greek-English Lexicon
νεανίας (neanias) — young man. νεᾱν-ίας, ου, Epic dialect and Ionic dialect νεηνίης, εω, ὁ, dative plural νεανίοις [Refs 3rd c.BC+]: (νεάν):—young man, [Refs 8th c.BC+]: without a substantive in [Refs 5th c.BC+]
2. frequently with the sense of a youth in character, i.e. either in good sense, impetuous, active, [Refs 5th c.BC+]; or in bad sense, hot-headed, wilful, headstrong, [Refs 5th c.BC+]
II. as masculine adjective, youthful, νεανίαι τὰς ὄψεις [Refs 5th c.BC+]
II.2. of things, etc., new, young, fresh, νεανίαις ὤμοισι [Refs 5th c.BC+]; ν. λόγοι rash, wilful words, [Refs 5th c.BC+] is trisyllable in [Refs 5th c.BC+]; compare νεανικός.]