scornful
Feeling or showing mean disrespect toward someone or something.
Scornful means showing contempt or disdain for someone or something you consider worthless or beneath you. When you're scornful, you dismiss something with cold superiority, as if it doesn't even deserve your attention.
A scornful look combines disgust with a sense of superiority, like when someone rolls their eyes and turns away from an idea they think is ridiculous. You might hear a scornful laugh when someone mocks a suggestion they find absurd. A person might speak in a scornful tone that makes others feel small or foolish.
The word comes from the noun scorn, which means open contempt or disrespect. Being scornful is different from simply criticizing something. Criticism can be constructive and helpful, but scorn dismisses things completely. A teacher might criticize your essay to help you improve it, but a scornful classmate might sneer at your ideas without offering anything useful.