sourdough

noun

1. (countable, uncountable)A type of bread dough leavened with yeast and lactobacilli that produce acids giving a sour taste.
2. (countable, slang)An old-timer, especially in Alaska.

   “The troops went for those fresh tomatoes like sourdoughs going for gold in the Klondike.”

3. (Yukon, countable)A permanent resident of the territory. Someone who has lived in the Yukon during all four seasons.
4. (countable, historical)A 49er, a California Gold Rush miner.
5. (countable, obsolete, uncountable)Leaven; an agent that makes dough rise.
6. (colloquial, dated)A long-time resident of Alaska.