to attack someone (especially verbally) unfairly in a deceitful, underhand, or treacherous manner, especially when they're not present in the place or situation that it happens. (as if stabbing them in the back). See backbite.
To attack (someone or something) with abusive language; to revile, to vilify.
To criticize (someone or something) in an abusive or harsh manner.
To use abusive or harsh words.
Of, characterized by, or relating to abusive or harsh criticism.
Which has been abusively or harshly criticized; also, deserving harsh criticism.