Sardonic (adjective)

Grimly mocking or cynical.

Origin:

Late latin sardonicus, from greek sardonios, from sardonios, a sardinian plant whose juice, when mixed with that of another plant, was supposed to cause spasms resembling those of laughter.

Examples:

1. He gave a sardonic smile.
2. The comedian's sardonic wit entertained the audience.
3. She had a sardonic sense of humor.
4. The novel was filled with sardonic observations.
5. His sardonic comments made the others uncomfortable.