FILLING n.
That which is used to fill a cavity or any empty space, or to supply a deficiency; as, filling for a cavity in a tooth, a depression in a roadbed, the space between exterior and interior walls of masonry, the pores of open-grained wood, the space between the outer and inner planks of a vessel, etc.
INDICATOR n.
That which indicates the condition of acidity, alkalinity, or the deficiency, excess, or sufficiency of a standard reagent, by causing an appearance, disappearance, or change of color, as in titration or volumetric analysis.