is that so

[is that so] {informal} 1. Oh, indeed? That's interesting. - Usedin simple acceptance or reply.

"The Republicans have pulled a trickat city hall." "Is that so?"

2. Surely not? - Used in disbelief orsarcasm.

"The moon is made of green cheese." "Is that so?"

"I'mgoing to take your girlfriend to the dance," said Bob. "Oh, is thatso!" said Dick. "Try it and you'll be sorry."