Lexical Definition

‎ἄθεσμος‎ áthesmos (ath'-es-mos) lawless ^G:A
from ‎Α‎ (as a negative particle) and a derivative of ‎τίθημι‎ (in the sense of enacting)

wicked.

• lawless, i.e. (by implication) criminal

Abbott-Smith

**† ἄθεσμος, -ον (< θεσμός, law, custom), [in LXX: III Mac 5:12 6:26*;]
lawless, esp. of those who violate the law of nature and conscience (cf. MM, VGT, s.v.): II Pe 2:7 3:17.†
SYN.: ἀθέμιτος, ἄνομος, κακός, πονηρός, φαῦλος (v. Tr., Syn., §lxxiv; DCG, ii, 821b).

Abbott-Smith References

Liddell-Scott-Jones

ἄθεσμος, ον,

={ἀθέσμιος}, [LXX+1st c.AD+]. adverb -μως[LXX+5th c.AD+]