Meaning of “leader” - Learner’s Dictionary

leader

noun [ C ] uk us /ˈliːdər/
PERSON IN CONTROL

B1 a person in control of a group, country, or situation:

a religious leader
Who's the leader of the Democratic Party in the Senate?
WINNER

someone or something that is winning during a race or other situation where people are competing:

He's fallen two laps behind the leaders.
Microsoft is a world leader in software design.

(Definition of “leader” from the Cambridge Learner’s Dictionary © Cambridge University Press)