Lexical Definition

‎ἄγνωστος‎ ágnōstos (ag'-noce-tos') unknown ^G:A
from ‎Α‎ (as negative particle) and ‎γνωστός‎

unknown.

Abbott-Smith

** ἄγνωστος, -ον (< γινώσκω), [in LXX: Wi 11:18 18:3, II Mac 1:19 2:7 (Cremer, 157)*;]
unknown: Ac 17:23 (cf. MM, VGT, s.v.).†

Abbott-Smith References

Liddell-Scott-Jones

ἄγνωστος, ον,

unknown, τινί[Refs 8th c.BC+]; unheard of, forgotten,[Refs 5th c.BC+]; unfamiliar, [Refs 4th c.BC+]

__2 not to be known, ἄγνωστόν τινα τεύχειν[Refs 8th c.BC+]; ἀγνωστστατοι γλῶσσαν most unintelligible in tongue, [Refs 5th c.BC+]
__3 not an object of knowledge, unknowable, ἄλογα καὶ ἄ.[Refs 5th c.BC+]; in comparative, harder to know, [Refs]adverb -τως[Refs 5th c.AD+]
__4 as the name of a divinity at Athens, νὴ τὸν Ἄγνωστον Ps.-[NT+2nd c.AD+]
__II active, notknowing, ignorant of, ψευδέων[Refs 5th c.BC+]adverb -τως inconsiderately, [Refs 1st c.BC+]

_{LSJ Scripture Refs: Acts.17.23}