'Forty-niner' definitions:

Definition of 'forty-niner'

(from WordNet)
noun
A miner who took part in the California gold rush in 1849

Definition of 'Forty-niner'

From: GCIDE
  • Forty-niner \For`ty-nin"er\, n. One the miners who took part in the California gold rush in
  • 1849; an argonaut. [Colloq., U. S.] [Webster 1913 Suppl.]