grout 
(grout)
(grout)n.
1.
a. A thin mortar used to fill cracks and crevices in masonry.
b. A thin plaster for finishing walls and ceilings.
2. often grouts Chiefly British Sediment; lees.
tr.v. grout·ed, grout·ing, grouts
To fill or finish with a thin mortar or plaster.
[Middle English, grain used for making malt, mud, from Old English grūt, coarse meal.]
grouter n.