Sentence:  Despite efforts to curb hate speech, eradicate bullying and extend tolerance, a culture of <WSD>nastiness</WSD> has metastasized in which meanness is routinely rewarded, and common decency and civility are brushed aside. 
Meaning of the word marked with <WSD> tags:  Indecency; corruption; unkindness, meanness, spite, harshness, cruelty.