Lexical Definition

‎ἀπειλέω‎ apeiléō (ap-i-leh'-o) to threaten ^G:V
of uncertain derivation

threaten.

• to menace
• by implication, to forbid

Abbott-Smith

ἀπειλέω, -ῶ (ἀπειλή), [in LXX: Na 1:4 (גּער), Is 66:14 (זעם), Si 19:17, al.;]
to threaten: I Pe 2:23; mid., Ac 4:17 (v. MM, VGT, s.v., and cf. προσαπειλέω).†

Abbott-Smith References

Liddell-Scott-Jones

ἀπειλέω,

__B3rd.pers.dual imperfect active ἀπειλήτην, Epic dialect for ἠπειλείτην, [Refs 8th c.BC+]: later Epic dialect present ἀπειλείω [Refs 4th c.AD+]:— hold out either in the way of promise or threat, and therefore:
__B.I sometimes in good sense, promise, οὐδ᾽ ἠπείλησεν ἄνακτι.. ῥέξειν κλειτὴν ἑκατόμβην[Refs 8th c.BC+]; also, boast or brag, ὥς ποτ᾽ ἀπειλήσει.1; ἦ μὲν ἀπείλησας βητάρμονας εἶναι ἀρίστους[Refs 8th c.BC+]
__B.II commonly in bad sense, threaten, in [Refs 8th c.BC+] spake a threatening speech, [Refs 8th c.BC+]; ἀπειλὰς ἀ., see at {ἀπειλ; δείν᾽ ἀπειλήσων ἔπη} [Refs 5th c.BC+]: frequently with neuter pronoun or adjective, ἀ. τόγε θυμῷ[Refs 8th c.BC+]; ταῦτα, πολλὰ ἀ., [Refs 5th c.BC+]
__B.II.2 with accusative of the thing threatened, θάνατον ἀ. ὃς ἂν..[Refs 5th c.BC+]; ἠπείλησαν τοὺς ἄρχοντας threatened them with the prefects, [Refs 4th c.AD+]
__B.II.3 dependent clauses were added in future infinitive, γέρας.. ἀφαιρήσεσθαι ἀπειλεῖς[Refs 8th c.BC+]: rarely in present infinitive, ἠπ... ἑλκέμεν[Refs 8th c.BC+] in aorist infinitive, [Refs 5th c.BC+]
__B.II.4 ἀ. ὅτι.., ὡς.., [Refs 5th c.BC+]; ἀ. τινί, εἰ μή.. [Refs]
__B.III passive, ἀπειλοῦμαι, of persons, to be terrified by threats, [Refs]
__B.III.2 of things, τὰ ἀπειληθέντα, ={ἀπειλαί}, [Refs 5th c.BC+]
__B.IV later in middle, with aorist 1 -ησάμην[Refs 2nd c.AD+]: with infinitive, forbid with threats, ἀπειλησώμεθα αὐτοῖς μηκέτι λαλεῖν[NT]

_{LSJ Scripture Refs: Acts.4.17}