The Kaf Hahayyim in Yoreh Deah often cites a sefer whose name he abbreviates with the rashei teivot הל''פ. I can't find this acronym in his luach rashei teivot at the beginning of Yoreh Deah volume 1, ...
Many wedding invitations written in Hebrew that I've seen have the abbreviations נ"י - after the groom's name - and תחי' - after the bride's name. (Example) Sometimes they are slight alterations ...
There is an acronym for the liquids that make things able to be made ritually impure. The Halacha is in order for fruit and the like to be made ritually impure it has to be made wet with these ...