Something can be described as invidious when it is resentful, discriminatory or envious, as in: "Fred was angered by the invidious gossip about his divorce being spread by his ex-wife's allies."
The adjective invidious is used to describe an act, thought, opinion or critique that is full of ill will or prejudice. It comes from a Latin word that means "hostile." When the captain of a cheerleading squad says nasty things about an opposing cheer team's skills, work ethic, and uniforms, those are invidious comments.