three-day event is a noun meaning "an equestrian competition; the first day is dressage; the second is cross-country jumping; the third is stadium jumping". It carries one recorded sense.
an equestrian competition; the first day is dressage; the second is cross-country jumping; the third is stadium jumping
Definitions, synonyms and semantic relations for three-day event come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.