Definition of "on the spot"

on the spot

prepositional phrase
1. (idiomatic) At that very moment.
2. (idiomatic) Having to answer or decide without warning or preparation.
3. (idiomatic) In a particular place.
  Quotations
  I had accepted an engagement to go out with Mystofilms Ltd. in Fake of Dead Man's Bush—the dwarf-men picture, you know, taken on the spot among the Australian bushmen.
  1928, Dorothy L. Sayers, “The Abominable History of the Man with Copper Fingers”, in Lord Peter Views the Body
  […] on October 29, 1888, the Russian imperial train was derailed at Borki by defective track, and twenty-one persons were killed. Although these did not include the Emperor Alexander III, who escaped with a bruising, a footman serving coffee to him at the critical moment, and his dog, which was lying on the floor beside him, were both killed on the spot.
  1945 September and October, C. Hamilton Ellis, “Royal Trains—V”, in Railway Magazine, pages 251–252