in·di·ca·tor

/ˈındəˌkeıtɚ/ noun, pl -tors [count]

1 : a sign that shows the condition or existence of something

Economic indicators suggest that prices will go up.

— often + of

The size of the new building is an indicator of how much the company has grown.

Her expression is usually a good/reliable indicator of how she's feeling.

2 a : a pointer or light that shows the state or condition of something

a control panel with various indicator lights

2 b : a device that shows a measurement : ↑gauge

an airspeed indicator

2 c Brit : ↑turn signal