(pol'ē-nū'klē-ō'ti-dās'ĕz), 1. Enzymes catalyzing the hydrolysis of polynucleotides to oligonucleotides or to mononucleotides; for example, phosphodiesterases, nucleases. 2. Term once applied to the two polynucleotide phosphatases, 2'(3')- and 5'-, which do not cleave internucleotide links.