That which causes fermentation, as yeast, barm, or fermenting beer.
- Something, such as a yeast, bacterium, mold, or enzyme, that causes fermentation.
- A state of agitation or of turbulent change or development.
- An agent that precipitates or is capable of precipitating such a state; a catalyst.
- To produce by or as if by fermentation.
- To cause to undergo fermentation.
- To make turbulent; excite or agitate.
- To undergo fermentation.
- To be in an excited or agitated state; seethe.