BT BM 52b(45) :דתרי זלזולי לא מזלזלינן ביה‏ : we do not establish two lowerings of its value [i.e. of the coin with respect to the tithe]
See the entire entry for zlzwl n.m. cheapening

BT BM 52b(45) :דתרי זלזולי לא מזלזלינן ביה‏ : we do not lower its price twice
See the entire entry for zll vb. to be of little value