"Pernicity" is a word that describes something that is destructive or harmful in nature. However, if you are looking for synonyms for this word, there are a number of options to choose from. Some synonyms for "pernicity" include malignancy, toxicity, venomousness, virulence, and lethality. All of these words describe something that is dangerous or harmful in some way. Other options may include words like malevolence, malice, or spitefulness, which imply a more intentional act of harm. No matter which synonym you choose, the key takeaway is that it describes something that is harmful and has the potential to cause damage or inflict pain upon those who encounter it.