Bellwether (noun)

1. A leader or indicator of a group or trend.
2. A sheep, esp. a castrated ram, with a bell worn around its neck, used to lead the flock.

Origin:

Bellwether, from bell + wether (a castrated male sheep that leads the flock), is a word meaning a leader or indicator of a group or trend.

Examples:

1. The stock market is often seen as a bellwether for the economy.
2. He was a bellwether in the industry, setting trends for others to follow.
3. The bellwether sheep led the flock to fresh pastures.
4. The company was considered a bellwether in the technology sector.
5. The bellwether's performance is closely watched by investors.