labor leader means "a leader of a labor movement".
Is labor leader a common word?
labor leader is banded "Rare" — specialist or archaic — most readers will not have met it. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.
Definitions, synonyms and semantic relations for labor leader come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.