What is the definition of verbal irony?

Verbal irony is saying something that is exactly or almost the opposite of what a person means.
Usually it is called “sarcasm.”
Example:
##1.##There’s a student who fails at a particular exam. When his classmate asks him about his score, he says, “Very, very great! I bet I am the first honor this period.”
##2.## Mary asks a question to Kris and Kris answers it in nonsensical way. Mary is then annoyed and she says, “Nice answer! Very helpful!”
We usually have the verbal irony if we are so annoyed on a person or if a happening is not favor with ours.