The Greek adjective athōos means innocent, guiltless, or not deserving punishment. It is formed from a- (not) + thōē (penalty/punishment). It appears only twice in the NT: both times in Matthew 27, at the trial and crucifixion of Jesus. First, Judas acknowledges he has betrayed innocent blood (Matthew 27:4); then Pilate declares he is innocent of this man's blood (Matthew 27:24). The word thus frames the most unjust execution in history with a declaration of legal innocence.
The double declaration of Jesus' innocence (athōos) at His trial is not incidental — it is central to the atonement. The substitutionary sacrifice requires an unblemished lamb (1 Peter 1:19). Jesus was condemned as guilty so that we, who are guilty, could be declared innocent. The Passover lamb had to be without defect; Jesus is without sin. The high priest at Yom Kippur had to be pure; Jesus is the holy, blameless, pure High Priest (Hebrews 7:26). The innocent one died for the guilty. That is the gospel.