General:
* Loaf
* Staff of life
* Dough
* Bakery
* Crust
More specific:
* For specific types of bread:
* Baguette
* Sourdough
* Rye
* Ciabatta
* For bread used for a specific purpose:
* Toast
* Cracker
* Roll
* Bun
* For bread as a metaphor:
* Sustenance
* Food
* Nourishment
The best synonym will depend on the specific meaning and context in which you are using the word "bread".