Ancient Languages/Greek letters


I recently purchased two old mosaics - one of Mary the Mother of God holding Jesus. On the top left are  the initials MP (joined together) and on the right are OV, which I found to mean Mother of God. However, my question is about the other mosaic which is of Jesus Christ. It has initials as well - an ISigma and XSigma. I have researched and only found IC XC on old mosaics of Christ. Therefore I am wondering why they didn't use the usual "C" but instead used the ancient sigma sign.
I can send pictures if it would help. Thanks


the Greek  capital letters MP  are the abbreviation for the ancient Greek noun MHTHP (in small letters: Μήτηρ transliterated as “Mētēr)) meaning “mother”, while the Greek  capital letters ΘΥ (not: OV) are the abbreviation for the ancient Greek noun ΘΕΟΥ (in small letters: Θεού  transliterated as “Theou”) meaning “of God”.

In short, the acronym ΜΡ that  represents the Greek capital characters Mi (M) and Rho(P), i.e. the first and last letters of MHTHP, and the acronym  ΘY  that  represents the capital Greek characters Theta (Θ) and Ypsilon (Y), i.e. the first and last letters of  ΘΕΟΥ) means “Mother of God” since MHTHP/Μήτηρ/Mētēr (nominative case)means "Mother" and ΘΕΟΥ/Θεού/Theou (genitive case) means "of God".

As for the other mosaic which is of Jesus Christ and has the abbreviation  “ISigma and XSigma “, please note that “ISigma and XSigma” can be written either  as  IΣ  XΣ or  as IC and ΧC with  a  C  which is the so-called “lunate sigma”, an alternate form of the sigma, the  18th letter of the ancient Greek alphabet usually written as Σ in its upper case.

So, IC  ΧC or IΣ  XΣ are the abbreviations for the ancient Greek words  ΙΗΣΟΥΣ  ΧΡΙΣΤΟΣ or ΙΗΣΟΥC ΧΡΙΣΤΟC  (in small letters: Ἰησοῦς Xριστός, transliterated as "Iesous Christos") meaning “Jesus Christ”.

The acronym IC / IΣ is composed of a Iota (I)  and a Sigma  (Σ or C) , i.e. the first and last letter of  ΙΗΣΟΥΣ / ΙΗΣΟΥC transliterated as IESOUS, while ΧC / XΣ is composed of a Chi (X)  and a Sigma  (Σ or C), i.e. the first and last letter of  ΧΡΙΣΤΟC / ΧΡΙΣΤΟΣ transliterated as CHRISTOS.

To conclude, the  lunate sigma C (upper case) -which is known as "lunate sigma" because its crescent shape resembles a half moon and the Latin word for moon is just “luna”- corresponds to the capital letter  Σ  whose small letter is “σ “ that appears in any position of a Greek word, except for the final letter,  where it becomes “ς “ .

Such a lunate sigma began to be used in handwritten Greek during the Hellenistic period (4th and 3rd centuries BC), when the epigraphic form of Σ was simplified into a C-like shape.

This "C" became the universal standard form of Sigma during late antiquity and the Middle Ages and  it is still widely used in decorative typefaces in Greece, especially in religious and church contexts as well as in some modern print editions of classical Greek texts.

Hope this is clear enough.

Best regards,

Ancient Languages

All Answers

Answers by Expert:

Ask Experts




I am an expert in Latin & Ancient Greek Language and I'll be glad to answer any questions concerning this matter.


Over 25 years teaching experience.

I received my Ph.D. in Classics (summa cum laude) from Genova University (Italy).

This expert accepts donations:

©2016 All rights reserved.