[bell.weth.er] n [ME, leading sheep of a flock, leader, fr. belle bell + wether; fr. the practice of belling the leader of a flock] (13c): one that takes the lead or initiative: leader; also: an indicator of trends
BELLWETHER
Meaning of BELLWETHER in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012