1) Christian iconography 2) Christian symbol 
A Christogram is a monogram or combination of letters that forms an abbreviation for the name of Jesus Christ, traditionally used as a Christian symbol. As in the case of Chrismon, the term Christogram comes from the Latin phrase `Christi Monogramma`, meaning `monogram of Christ`.{dubious|Etymology|date=January 2014}{Failed verification|date=J...
A monogram made up of the Greek letters Chi and Rho, which look to us like X and P. These letters make up the start of the name of Christ in Greek.
a symbol of Christ, esp. the Chi-Rho.