lees: the sediment of a liquor (as wine) during fermentation and aging > Merriam-Webster

lees: Heavy sediment left in the barrel by fermenting wines; a combination of spent yeast cells and grape solids > winemag.com

lees: sediment consisting of dead yeast cells, grape pulp, seed, and other grape matter that accumulates during fermentation > Wine School of Philadelphia

We took this photo when we racked some of our wine off the lees (just taking the clean wine, taking care).