Meaning of INDICATOR in English
( 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.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012