The symbol is of pre-Christian origin. It is found on copper coins minted by
Herod I in 37 BC, interpreted as a
tr ligature representing
trikhalkon indicating the coin value.
Abbreviation for stauros The staurogram was first used to abbreviate
stauros (), the Greek word for
cross, in very early
New Testament manuscripts such as , and , almost like a
nomen sacrum, and may visually have represented
Jesus on the cross.
Monogram of Christ The Tau-Rho as a
Christian symbol outside its function as
nomen sacrum in biblical manuscripts appears from used as a
monogramma Christi alongside the
Chi-Rho and other variants, spreading to Western Europe in the 5th and 6th centuries.
In combination with alpha and omega Ephrem the Syrian (4th century) discusses a Christian symbol, apparently combining the Tau-Rho with
Alpha and Omega placed under the left and right horizontal arms of the Tau. Ephrem says that the Tau represents the cross of Jesus (prefigured by the outstretched hands of
Moses in ), the Alpha and Omega signify that the crucified Christ is "the beginning and end", and the Rho, finally, signifies "Help" ( ; classical spelling: ), because of the
numerological value of the Greek word being
100, represented by Rho as a
Greek numeral.
Tau and rho separately The two letters tau and rho can be found separately (not in ligature) as symbols already on
early Christian ossuaries.
Coptic Unicode block The staurogram is encoded by
Unicode in the
Coptic block, at , and as of Unicode 7.0 (2014) also in the
Ancient Symbols block, at . The Coptic block has a ligature of the full word σταυρός, where the τρ is represented by the staurogram, and two
lunate sigmas are attached to either side of the tau's horizontal bar, at . ==See also==