Labarum Meaning

First adopted by the Emperor Constantine after his conversion to Christianity. It is described as a pike bearing a silk banner hanging from a crosspiece, and surmounted by a golden crown. It bore a monogram of the first two letters (CHR) of the name of Christ in its Greek form. Later, the name was given to various modifications of this standard.
As to the monogram, it was a combination of the letter X, Chi, and P, Rho, the initial syllable of Christos.