Only a few decades ago, all entries in medical records were in handwriting. Necessary haste made abbreviations very desirable. Rx is just one of many. "s" with a line over it meant "sine = (Latin)without." "c" with a line over it meant
(Latin) cum = with. "q" meant each or every. I wonder if there is anywhere a collection of them. I hope wofahulicodoc,Alex Wiliams and doc_comfort will make additions to this.