leadership has 2 distinct synonyms spread across 2 of its 4 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the activity of leading
“his leadership inspired the team”
the body of people who lead a group
“the national leadership adopted his plan”
Synonyms, antonyms and the broader and narrower relations for leadership come from Princeton University’s WordNet. Full sources and licences.
the status of a leader
“they challenged his leadership of the union”
the ability to lead
“he believed that leadership can be taught”