Pronunciation (US) IPA (key): /ˈdʒin.jəs/ or /ˈdʒi.ni.əs/ (UK) IPA (key): /ˈdʒiː.nɪəs/ Audio (US)(file) Noun Singular genius Plural geniuses (countable) A genius is a person who is very smart. Albert Einstein is a genius. Wikiwand - on Seamless Wikipedia browsing. On steroids.Remove ads