'Stumper' definitions:

Definition of 'stumper'

From: WordNet
noun
A particularly difficult or baffling question or problem [syn: poser, stumper, toughie, sticker]

Definition of 'Stumper'

From: GCIDE
  • Stumper \Stump"er\, n.
  • 1. One who stumps. [1913 Webster]
  • 2. A boastful person. [Slang] [1913 Webster]
  • 3. A puzzling or incredible story. [Slang, U.S.] [1913 Webster]

Synonyms of 'stumper'

From: Moby Thesaurus