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.15.16Mark.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+]