Irony
Etymology
From Greek eirōneía, "dissimulation, feigned ignorance," from eírōn, the stock character who pretends to know less than he does. In Greek comedy the eírōn deflated the boastful braggart by playing dumb. That performance of feigned innocence is the seed of every later sense, from verbal irony to the dramatic kind an audience sees coming.
noun · /EYE-ruh-nee/
Saying or presenting one thing while meaning, or revealing, its opposite.
What it names
The gap between what is said and what is meant — the knowing wink that lets a listener catch a second, contrary layer beneath the surface.
Example
There was real irony in the fire station burning down while the crew was out giving a fire-safety talk.
Related idea
Sarcasm is a pointed, hostile subspecies of verbal irony aimed at wounding; irony can be gentle, structural, or entirely impersonal.