sourdough

noun5

1. •
   A type of bread dough leavened with yeast and lactobacilli that produce acids giving a sour taste.
2. •
   A permanent resident of the territory. Someone who has lived in the Yukon during all four seasons.
3. •
   (slang) An old-timer, especially in Alaska.

   • The troops went for those fresh tomatoes like sourdoughs going for gold in the Klondike. — 1944
4. •
   (historical) A 49er, a California Gold Rush miner.
5. •
   (no longer used) Leaven; an agent that makes dough rise.