the use of language that has a surface meaning opposite to what one actually intends to convey, as a means of expressing contempt or mockery;
e.g. His sarcasm was scathing, but also very humorous.
(noun)
an utterance that on the surface means the opposite of what one actually means, usually delivered as humor or in order to ridicule or mock something or someone;
e.g. He gave them sarcasm, which they found to be rude and disrespectful.