monogrammatic

In a fresco which dates from the middle of the fourth century in the "great cave" of the catacomb of Praetextatus, Alpha and Omega are found in connection with the monogrammatic cross.

The Catholic Encyclopedia, Volume 1: Aachen-Assize 1840-1916 1913

Thus the open cross is found in the epitaphs of the catacombs as early as the second century, and from the third to the sixth century the monogrammatic cross in its various forms appears as a regular part of the epitaphs.

The Catholic Encyclopedia, Volume 8: Infamy-Lapparent 1840-1916 1913

Nazianzen, wore an iron cross on her breast; we do not really know its shape; perhaps it was the monogrammatic one taken by her brother from her dead body.

The Catholic Encyclopedia, Volume 4: Clandestinity-Diocesan Chancery 1840-1916 1913

In the latter part of that century what is known as the "monogrammatic cross" makes its appearance; it closely resembles the plain cross, and foreshadows its complete triumph in Christian art.

The Catholic Encyclopedia, Volume 4: Clandestinity-Diocesan Chancery 1840-1916 1913