I. ˈində̇ˌkād.ə(r), -dēˌk-, -ātə- noun
Etymology: Late Latin, from Latin indicatus (past participle of indicare to indicate) + -or
1. -s : one that indicates: as
a. : an index hand (as on a dial) : pointer
b.
(1) : a pressure gauge
(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 so that the horsepower and other characteristics may be deduced
c. : a speed counter for an engine
d. : a registering dial (as on a dial telegraph)
e. : annunciator 2a
2. -s
a. : a substance (as a dye) used to show visually usually by its capacity for color change the condition of a solution with respect to the presence of free acid or alkali or some other substance (as in detecting the end point of a titration)
litmus and phenolphthalein are acid-base indicators
oxidation-reduction indicators
b. : tracer
radioactive indicators
3.
a. capitalized
[New Latin, from Late Latin]
: the type genus of the family Indicatoridae — see honey guide
b. -s : any bird of the genus Indicator : honey guide
4. -s
[so called from a belief that its occurrence indicates that there is ginseng nearby]
: virginia grape fern
5. -s : an organism or a kind of organism (as a species) or an ecological community that is so strictly associated with particular environmental conditions that its presence is indicative of the existence of these conditions in a particular environment
6. -s : a narrow pyritiferous seam the intersections of which with auriferous quartz veins are usually accompanied by an ore shoot in the vein
7. -s : a deciphering instruction accompanying a message: as
a. : a code or cipher designation of the key
b. : interrupter b
II. noun
: any of a group of statistical values (as level of employment and change in the price of industrial raw materials) that taken together indicate the health of the economy — see coincident herein lagging indicator herein leading indicator herein