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on earthand in creation; in the world
Fig. really; indeed; in fact. (Used as an intensifier after who, what, when, where, how.) What on earth do you mean?' How in creation do you expect me to do that? Who in the world do you think you are?
in any conditions in the world What on earth makes you say that? Why on earth would she ask you to join them? How on earth did you survive the heat? Who on earth would want to collect rocks? Where on earth could Casey have learned such behavior?
Usage notes: used to express great surprise that something could happen or exist
1. Also, in creation; in the world. Ever, anywhere, of all possible things. These phrases are all used for emphasis in questions or, less often, in a negative context. For example, What on earth is he doing with a spade? or Where in creation did that child go? or How in the world do you expect me to carry all those bags? [Late 1700s]
2. like nothing on earth. Incomparable. For example, That perfume smells like nothing on earth, or Her new hair color is like nothing on earth. [c. 1900]
Among all the possibilities: Why on earth did you put on that outfit?