Pronunciation (UK) IPA (key): /ˈliː.də(r)/ (US) (Canada) IPA (key): /ˈlidɚ/ Audio (US)(file) Noun Singular leader Plural leaders Leader is on the Academic Vocabulary List. (countable) A leader is someone who leads others and has them following him. Kings, presidents, governors, and mayors are all different types of leaders. (countable) A leader is someone who is the best at what he does. Johntech is a leader in the microprocessor industry. Wikiwand - on Seamless Wikipedia browsing. On steroids.Remove ads