>
> The words "poolish" & "biga" have often been used with
> reference to sour dough starters.
>
> I can't find them in my dictionaries (Chambers & Collins) nor
> in the online dictionary "dictionary.com".
>
> I was interested in their etymology. Can anyone help?


Sure. I've seen these terms used primarily to refer to sponges that use
commercial yeast, but, in any case --

Poolish: A French term for a wet yeasted pre-ferment that's usually and
equal weight of flour to water.

Biga: An Italian word for any kind of pre-ferment. It can be wet or dry,
though English speaking bakers usually use it to refer to a dough-like
preferment where the water weight is roughly 60% of the dough weight.

In each, a small amount of yeast is added, and then the sponges are allowed
to ferment for a long period of time, anywhere from 4 to 14 hours, depending
on temperature and the amount of yeast added.

--
Jeff