Lexical Definition

‎ἀναμάρτητος‎ anamártētos (an-am-ar'-tay-tos) sinless ^G:A
from ‎Α‎ (as a negative particle) and a presumed derivative of ‎ἁμαρτάνω‎

that is without sin.

• sinless

Abbott-Smith

ἀναμάρτητος, -ον (< ἁμαρτεῖν), [in LXX: De 29:19 (18) II Mac 8:4 12:42*;]
1. without missing, unerring (Xen.).
2. In moral sense, faultless (Plat.), without sin: Jo 8:7 (v. Cremer, 102, 634; MM, VGT, s.v.).†

Abbott-Smith References

Liddell-Scott-Jones

ἀναμάρτητος-ητος, ον,

making no mistake, unerring, [Refs 5th c.BC+]

__2 in moral sense, blameless, [Refs 5th c.BC+]; sinless, [NT+1st c.AD+].; ἀ. πολιτεία a faultless form of government, [Refs 4th c.BC+]; ἀ. πρός τινα having done no wrong to a person, [Refs 5th c.BC+]; ἀ. τινός guiltless of a thing, [Refs 5th c.BC+]to preserve from error, [Refs 4th c.BC+]. adverb -τως without fail, unerringly, [Refs 5th c.BC+]; without making a mistake, Ps.-[Refs 2nd c.AD+]; inoffensively, [[Refs 4th c.BC+]
__II of things, not done by fault, done unavoidably, συμφορά[Refs 5th c.BC+]
__II.2 unfailing, [Refs 2nd c.AD+]

_{LSJ Scripture Refs: John.8.7}