indicator
n. countablen. a sign or signal that shows the condition or level of something. You use it to understand how a situation is changing, like how a high price shows a strong market.
n. a metric, sign, or substance that provides specific information about the state or level of a broader system. In technical contexts, it refers to a chemical that changes colour to signal a specific condition or a species whose presence reflects environmental health.
High unemployment is a negative economic indicator.
The chemist added a few drops of indicator to the solution to see if it was acidic.
Ecologists monitor the population of certain amphibians as a primary indicator of wetland health, as their permeable skin makes them exceptionally sensitive to chemical pollutants.
From Late Latin indicātor (“one who points out”), from Latin indicō (“point out”). By surface analysis, indicate + -or; see indicate.
Often followed by the preposition 'of' to specify what is being measured or signaled.