Ma'anar ƙamus na kalmar "exonuclease" wani enzyme ne wanda ke haifar da kawar da ragowar nucleotide daga ƙarshen DNA ko RNA kwayoyin ta hanyar mataki-mataki, yana ci gaba daga rukunin 5'-phosphate ko 3'-hydroxyl. . A wasu kalmomi, wani enzyme ne da ke rushe kwayoyin nucleic acid ta hanyar cire nucleotides daya bayan daya daga ƙarshen DNA ko RNA strand.
