Amongst the most violent against him was Mrs. Bennet, whose dislike of his general behaviour was sharpened into particular resentment by his having slighted one of her daughters.' What is the definition of slighted as it is used in this sentence?

The definition of the slighted would be attack or insult. It is because in the sentence, it was obvious that the person dislike him that the proper gesture of what he is going to do to the person was to do something that he deserves which is attack or insult one of her daughters.