chris·mon 
(krĭsmən)
(krĭsmən)n.
1. See Chi-Rho.
2. A decoration or ornament in the form of a Chi-Rho or other Christian emblem.
[New Latin Chrīs(tī) mon(ogramma), monogram of Christ : Latin Chrīstī, genitive of Chrīstus, Christ; see CHRIST2 + Late Latin monogramma, monogram; see MONOGRAM.]