Bread-Bakers v102.n038.4

Percent hydration is the amount of water expressed as a percentage of the 
weight of flour.  If you were using one pound of flour, a 70% hydration 
dough would use 0.7 lb, or about 11 oz of water.  Other ingredients may 
also be expressed similarly as  a percentage of the flour weight, where the 
weight of flour is taken to be 100%.

Slacker dough is softer, with slower recoil when kneaded, and usually is 
wetter (but could also, in some situations, be made with less gluten).

Diane Brown