The Greek ekpneō means to breathe out completely — to expire. In the New Testament it is used exclusively and specifically of Jesus' death on the cross. Mark 15:37 and 15:39 and Luke 23:46 all use ekpneō to describe the moment of Jesus' death. The word is a medical-literary term for the final exhalation — the breath going out without return.
The precision of ekpneō for Christ's death is significant. He did not simply lose consciousness or collapse — He 'breathed out' life itself. Luke 23:46 is the most moving context: 'Jesus called out with a loud voice, Father, into your hands I commit my spirit. When he had said this, he breathed his last (ekpneō).' The loud voice before death underscores the voluntary nature of the sacrifice — He laid down His life; it was not taken from Him (John 10:18). The breath that came out in creation (Genesis 2:7) returned through the One whose ekpneō purchased our life.