Lindisfarne Gospels: 10
They are generally called nomina sacra if they are one of the words on a list of 15 or so words that have been so abbreviated in the earliest Greek manuscripts only for their sacred use but not for the profane use. I have paraphrased the explanation from this page. Nomina Sacra in P46
Nomina sacra are special abbreviations which appear in Christian texts. Unlike most abbreviations, which are supposedly intended to save time (see Abbreviations in P46), nomina sacra are used to set certain holy words apart from the rest of the text. This is inferred from the fact that these words are abbreviated in their sacral usages but not in profane usages (e.g. ὑΐοϲ, 'son' is contracted to υϲ when it refers to Jesus, the Son of God, but the same word is not contracted in other usages).
Naturally, in Greek and Latin, because of case endings, the last letter in the name will indicate the case, so the nomina sacra does not possess an immutable shape. In Latin Deus is either DS, DI, DM, and DO, for example. Dominus is DNS, DNI, etc. and Christus is XP, XPS, XPI, etc. with Greek letters later mixed into the Latin. So there was a weakened relationship with the phonetic values of letters and a stronger relationship with a constant visual relationship across languages, yet still representing the case endings.
I have found so far that further research into the nomina sacra has given me a lot to think about concerning how individuals and religious communities regard the name of God. People approach the name of God with reverence and accord it greater recognition and visibility while distancing it from the phonetic system.
Believers are drawn to a symbol for God, then Jesus, and later the saints, which crosses boundaries of time and space. But the old connections are sometimes forgotten and new ones need to be forged. Reading about the nomina sacra has inspired me to do further reading in how the name of God is represented in the Hebrew scriptures.
I will post soon on the nomen sacrum for the name of Jesus in the Lindisfarne gospels.