A Madonna is a representation of Mary, either alone or with her child Jesus. These images are central icons for both the Catholic and Orthodox churches. The word is from Italian "mia donna", meaning 'my lady'.
Alpha (Α or α) and omega (Ω or ω) are the first and last letters of the Greek alphabet, and a title of Christ and God in the Book of Revelation. This pair of letters are used as Christian symbols, and are often combined with the Cross.