IS THAT SO

{informal} 1. Oh, indeed? That's interesting. - Used in simple acceptance or reply. * /"The Republicans have pulled a trick at city hall." "Is that so?"/ 2. Surely not? - Used in disbelief or sarcasm. * /"The moon is made of green cheese." "Is that so?"/ * /"I'm going to take your girlfriend to the dance," said Bob. "Oh, is that so!" said Dick. "Try it and you'll be sorry."/