The Greek noun alektōr (ἀλέκτωρ) refers to a rooster or cock. The word appears exclusively in the Gospel accounts of Peter's denial of Jesus, where the crowing of the rooster was the signal Jesus had foretold.
The rooster's crow is one of the most painful and mercy-laden details of the Passion. Jesus predicted Peter's denial with startling specificity (Mark 14:30). The crow broke Peter to tears. The rooster became an instrument of divine mercy — the wake-up call that led to Peter's restoration. From early Christianity, the rooster on church spires has symbolized vigilance and the dawn of new beginning.