What is a disrespectful or scornfully abusive remark or act called?
An insult is an expression or statement (or sometimes behavior) which is disrespectful or scornful. Insults may be intentional or accidental.
Backhanding is referred to as slapping someone using the back of the hand instead of the palm—that is generally a symbolic, less forceful blow. Correspondingly, a backhanded (or left-handed) compliment, or asteism, is an insult that is disguised as, or accompanied by, a compliment, especially in situations where the belittling or condescension is intentional.
Examples of backhanded compliments: "That skirt makes you look far thinner.", insinuating hidden fat, with the implication that fat is something to be ashamed of; "I like you. You have the boldness of a much younger person.", insinuating decline with age.