Scribal abbreviation by "contraction" and was mostly a Christian usage for sacred words, Nomina Sacra; non-Christian sigla usage usually limited the number of letters the abbreviation comprised and omitted no intermediate letter. One practice was rendering an overused, formulaic phrase only as a siglum: DM for "Dis Manibus" ("Dedicated to the Manes"); IHS from the first three letters of "ΙΗΣΟΥΣ"; and RIP for "requiescat in pace" ("Rest in Peace") because the long-form written usage of the abbreviated phrase, by itself, was rare. According to Trabe, these abbreviations are not really meant to lighten the burden of the scribe but rather to shroud
Latin Wikipedia When occasionally a term for a modern concept cannot be found, the customary practice is to do exactly what most other languages do: to borrow an international word (often from a Romance language or English). Such direct borrowing was done for the particle names and and for the unit of temperature . The word is given a Latin morphology if this can be done easily, or, if not, used unchanged in its foreign form; but many international words already have a Latin or Graeco-Latin appearance, because Greek and Latin have always served as sources of new scientific terminology. Vicipaedia made