Lexical Definition

‎ἀσύνετος‎ asýnetos (as-oon'-ay-tos) senseless G:A
from ‎Α‎ (as a negative particle) and ‎συνετός‎

foolish, without understanding.

Usage: 9 forms in 10 verses
Form Translated As     In Verse(s)
ἀσύνετοσ foolish Rom.1.21
ἀσύνετοί without understanding Matt.15.16 • Mark.7.18
ἀσυνέτῳ without understanding Rom.10.19
ἀσυνέτουσ foolish Rom.1.31
ασύνετοσ senseless LXX.Ps.92.6
ασύνετοι senseless LXX.Ps.76.5
ασυνετώτερόσ more senseless LXX.Job.13.2
ασυνέτω a senseless LXX.Deut.32.21
ασυνέτου senseless LXX.Ezek.45.20

Abbott-Smith

ἀ-σύνετος, -ον [in LXX: De 32:21 (נָבָל), Jb 13:2 (נפל), Ps 91 (92):6 (כְּסִיל), Ps 75 (76):5, Wi2, Si6*;]
without understanding or discernment: Mt 15:16, Mk 7:18 (Swete, in l.), Ro 1:21, 31 10:19 (for an ex. of its use in the moral sense, v. MM, s.v.).†

Abbott-Smith References

Book Refs
Deuteronomy 32:21
Job 13:2
Psalms 76:5 · 92:6
Matthew 15:16
Mark 7:18
Romans 1:21 · 1:31 · 10:19

Liddell-Scott-Jones

ἀσύνετος,

Attic dialect ἀξ-, ον, void of understanding, witless, [Refs 5th c.BC+]: comparative, [Refs 5th c.BC+]; τί τάδ᾽ ἀσύνετ; what folly is this? [Refs 5th c.BC+]. adverb -τως[Refs 1st c.AD+]

__2 with genitive, not able to understand, λόγου[Refs 1st c.AD+]
__II not to be understood, unintelligible, [Refs 5th c.BC+]. adverb -τως[Refs 2nd c.BC+]