hyperon Syllabification: (hy·per·on)Pronunciation: /ˈhīpəˌrän/Definition of hyperon noun Physics an unstable subatomic particle classified as a baryon, heavier than the neutron and proton. Origin: 1950s: from hyper- 'beyond, over' + -onhyperon in other Oxford dictionaries Definition of hyperon in the British & World English dictionary