The Greek word pascha is a transliteration of the Aramaic/Hebrew pesach (Passover). It refers to the Passover feast — the annual Jewish commemoration of the Exodus deliverance — and to the Passover lamb itself. The New Testament identifies Jesus as the fulfillment of the Passover, the true Lamb of God.
Pascha sits at the center of the New Testament's understanding of atonement. Jesus was crucified on or around Passover — the timing is not incidental but providential, the substance being fulfilled in the shadow. John's Gospel presents Jesus as dying at the exact hour the Passover lambs were being slaughtered in the temple. Paul makes the identification explicit in 1 Corinthians 5:7: 'Christ, our Passover lamb, has been sacrificed.' This means the Exodus pattern — lamb slain, blood applied, death passes over, captives freed — is fulfilled in Christ. The Lord's Supper is the new Passover meal, the feast of the New Covenant. Every time believers gather at the table, they proclaim the death of Christ until He comes.