Scribal abbreviations (sigla) were abbreviations used by ancient and medieval scribes writing in Latin.

History
The use of abbreviations is due, in part, to exigencies arising from the nature of the materials employed in the making of records, whether stone, marble, bronze, or parchment. Lapidaries, engravers, and copyists were under the same necessity of making the most of the space at their disposal. Such abbreviations, indeed, were seldom met with at the beginning of the Christian era when material of all kinds was plentiful and there was consequently no need to be sparing in the use of it. By the third or fourth century, however, it had grown to be scarce and costly, and it became the artist's aim to inscribe long texts on surfaces of somewhat scanty proportions.
The Romans possessed an alphabet known by the name of Notae Tironienses (Tironian notes), which served the same purpose as our modern systems of stenography. Its use necessitated a special course of study and there is still much uncertainty as to the significance of the characters employed. Inscriptions cut in stone make the most frequent use of abbreviations. At certain late periods - for example in Spain in the Middle Ages, this custom becomes abused to such an extent as to result in the invention of symbols which are undecipherable.
Scribal abbreviations have entered the news in the twenty-first century because the recently revived Scottish Parliament needs to find out what the old codes of Scottish law written in Latin say. Those who have learned Latin without having also learned Latin palaeography find these abbreviations incomprehensible. At a recent count, there were well over fourteen thousand abbreviations.