A catalyst.
Something, such as a yeast or barm, that causes fermentation.
A gentle internal motion of the constituent parts of a fluid; fermentation.
A state of agitation or of turbulent change.
To stir up, agitate, cause unrest or excitement in.
To react, using fermentation; especially to produce alcohol by aging or by allowing yeast to act on sugars; to brew.
Accelerator; foot control for fuel flow.