Definition of indicator
1
: one that indicates: such as
a
: an index hand (as on a dial) : pointer
b(1)
: gauge sense 2b, dial sense 4a
(2)
: an instrument for automatically making a diagram that indicates the pressure in and volume of the working fluid of an engine throughout the cycle
2
: any of a group of statistical values (such as level of employment) that taken together give an indication of the health of the economy
3a
: a substance (such as litmus) used to show visually (as by change of color) the condition of a solution with respect to the presence of a particular material (such as a free acid or alkali)
b
: tracer sense 4b
4
: an organism or ecological community so strictly associated with particular environmental conditions that its presence is indicative of the existence of these conditions
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Merriam-Webster unabridged
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Time Traveler for indicator
The first known use of indicator was in 1666
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