isogamyPronunciation: /ʌɪˈsɒgəmi/Definition of isogamy noun [mass noun] Biology sexual reproduction by the fusion of similar gametes. Compare with anisogamy.Derivatives isogamete noun isogamous adjective Origin: late 19th century: from iso- 'equal' + Greek -gamia (from gamos 'marriage')isogamy in other Oxford dictionaries Definition of isogamy in the US English dictionary