Definition of "bullseye"

bullseye

/ˈbʊlzaɪ/

noun
plural bullseyes
1. (military, firearms) The centre of a target, inside the inner and magpie.
2. A shot which hits the centre of a target.
3. (darts) The two central rings on a dartboard.
4. A hard striped peppermint-flavoured boiled sweet.
5. (nautical, obsolete) Thick glass set into the side of a ship to let in light.
6. A hand-cancelled postmark issued by a counter clerk at a post office, typically done on a receipt for proof of mailing.
7. The central part of a crown glass disk, with concentric ripple effect.
8. A convex glass lens which is placed in front of a lamp to concentrate the light so as to make it more conspicuous as a signal; also the lantern itself.
  Quotations
  [I]nstead of the six pair of feet which should have protruded therefrom, the gleam of the bull's-eye showed but four.
  1874, Marcus Clarke, For the Term of his Natural Life, Penguin, published 2009, page 45
  He put on his fur coat and hat and went out into the hall. There he paused, hearing the slow heavy tread of the policeman on the pavement outside and seeing the flash of the bull's-eye reflected in the window.
  1890, Oscar Wilde, chapter XII, in The Picture of Dorian Gray
9. (military, by extension) A commonly-known reference point used when indicating the location or direction of something.
10. (architecture) An oculus.
11. (UK, slang) A £50 banknote.
12. (philately, informal) Any of the first postage stamps produced in Brazil from 1843.
interjection
1. A cry when someone hits the bullseye of a target.
2. (by extension) A response to a totally accurate statement.