1a n. fermenting dough, often a piece held over from a previous baking, used as a starter in baking bread, biscuits, etc.
See also: sourdough starter
1b n. (used attributively) made of sourdough.
See also: sourdough bread
2a n. Hist. sa prospector or miner who crossed the White, Chilcoot, or Dyea passes into the Yukon gold-fields before 1898, so called because his staple was sourdough bread.
See also: sourdough bread
2b n. a prospector, especially an experienced one who spends a lot of time in the wilderness.
2c n. any old hand in the Yukon or the Northwest Territories; an old-timer, as opposed to a greenhorn, or cheechako.
See also: cheechako ((n.))
3 n. bread made with dough started with sourdough (def. la).
See also: sourdough bread