OED [Etymology: late Latin sarcasm-us , < late Greek σαρκασμός , < σαρκάζειν to tear flesh, gnash the teeth, speak bitterly, < σαρκ- , σάρξ flesh]
Sarcasm: A sharp, bitter, or cutting expression or remark; a bitter gibe or taunt. Now usually in generalized sense: Sarcastic language; sarcastic meaning or purpose.
Wikipedia: The use of irony to mock or convey contempt.
Merriam-Webster.com: a sharp and often satirical or ironic utterance designed to cut or give pain
thefreedictionary.com: 1. A cutting, often ironic remark intended to wound. 2. A form of wit that is marked by the use of sarcastic language and is intended to make its victim the butt of contempt or ridicule. 3. The use of sarcasm.
John Knowles, A Separate Peace (19): " . . . this was my sarcastic summer. It was only long after that I recognized sarcasm as the protest of people who are weak."
Sarcasm Quotes from The Sarcasm Society
Groucho Marx: "If you find it hard to laugh at yourself, I would be happy to do it for you."
Mark Twain: "I didn't attend the funeral, but I
sent a nice letter saying I approved of it."
"If you don't read the newspaper, you are uninformed; if you do read the newspaper, you are misinformed."
Winston Churchill: "A modest little person, with much to be modest about."
Billy Wilder: "He has Van Gogh's ear for music."
Wittgenstein: "I don't know why we are here, but I'm pretty sure that it is not in order to enjoy ourselves."
Emo Phillips: "When I was a kid I used to pray every night for a new bicycle. Then I realised that the Lord doesn't work that way so I stole one and asked Him to forgive me."
Unknown: "Anyone who told you to be yourself couldn't have given you any worse advice."
Jules Renard: "I don't know if God exists, but it would be better for His reputation if He didn't."
Lily Tomlin: "I always wanted to be somebody, but now I realize I should have been more specific."
Ellen DeGeneres: "My grandmother started walking five miles a day when she was sixty. She's ninety-seven now, and we don't know where the hell she is."