Chi-rho

The Chi Rho (/ˈkaɪ ˈroʊ/; also known as chrismon) is one of the earliest forms of christogram, and is used by some Christians. It is formed by superimposing the first two (capital) letters—chi and rho (ΧΡ)—of the Greek word ΧΡΙΣΤΟΣ "Christ" in such a way that the vertical stroke of the rho intersects the center of the chi. The Chi-Rho thus symbolises specifically the status of Jesus as the risen Christ (Messiah).

The Chi-Rho symbol was used by the Roman emperor Constantine I (r. 306–337) as part of a military standard (vexillum). Constantine's standard was known as the Labarum. Early symbols similar to the Chi Rho were the Staurogram () and the IX monogram ().

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