Also found in: Wikipedia.
An exclamation of alarm, dismay, or disbelief. A: "I heard we're having a pop quiz tomorrow!" B: "Oh no! I haven't been keeping up with the readings!" A: "Oh no!" B: "What's wrong?" A: "Oh, I broke my favorite necklace. That has really ruined my day!"
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.