The Greek alektorophōnia means "the crowing of a rooster" — specifically as a time marker. It designates the third watch of the night, roughly 3:00 AM, when roosters typically begin to crow.
Mark 13:35 lists "cockcrow" as one of the four night watches — the disciples must be alert, for the master may return at any hour. The cockcrow is haunted by Peter's denial: "Before the rooster crows twice, you will disown me three times" (Mark 14:30). When the rooster crowed after Peter's third denial, Peter wept bitterly. The ordinary sound of a rooster became a piercing instrument of conviction. God uses the mundane to awaken the sleeping conscience.