Lexical Definition

‎ἀναίτιος‎ anaítios (an-ah'-ee-tee-os) innocent ^G:A
from ‎Α‎ (as a negative particle) and ‎αἴτιος‎ (in the sense of ‎αἰτία‎)

blameless, guiltless.

• innocent

Abbott-Smith

ἀν-αίτιος, -ον (< αἰτία), [in LXX: De 19:10, 13 21:8, 9 (נָקִי), Da LXX TH Sus 62, always of αἷμα (of. MM, VGT, s.v.)*;]
guiltless, innocent: Mt 12:5, 7.†

Abbott-Smith References

Liddell-Scott-Jones

ἀναίτιος, ον,

also α, ον [Refs 5th c.BC+]:—in the best authors, only of persons, not being the fault or cause of a thing, guiltless, ἀναίτιον αἰτιάασθαι[Refs 8th c.BC+]; ἀναίτιος ἀθανάτοις guiltless before the gods, [Refs 8th c.BC+]

__2 with genitive of things, guiltless of a thing, [Refs 5th c.BC+]; φόνου, κακῶν, [Refs 5th c.BC+] with infinitive, it is blamable to do, [Refs]
__II not being the cause, τὸ ἀ. τιθέναι ὡς αἴτιον[Refs 4th c.BC+]; having no cause, unjustifiable, κολάσεις[Refs 1st c.BC+]adverb -ως not in the form of a cause, ἀ. τὴν αἰτίαν ἔχειν[Refs 3rd c.AD+]; without assigning any reason, ὁλοσχερῶς καὶ ἀ. λεκτέον[Refs 6th c.AD+]
__III uncaused. [Refs 3rd c.AD+]: superlative, [Refs 5th c.BC+]. adverb -ως without a cause, [Refs 2nd c.AD+]