A sourdough is a type of bread made from a long-fermented dough that uses naturally occurring lactobacilli and yeast. It can also refer to a person who is an old-timer in a particular place, especially the western United States.
Sourdough bread is often seen as traditional and wholesome, while a sourdough person is seen as experienced and knowledgeable.
Examples:
She bakes delicious sourdoughs every week.
The sourdough at the bakery is always fresh and tasty.
The sourdough, who has lived here for many years, knows all the best fishing spots.
The old sourdough told us stories of the gold rush.
I could eat a whole basket of sourdoughs in one sitting.
The sourdough's bread is so good, it's like magic.