gametophytePronunciation: /gəˈmiːtə(ʊ)fʌɪt/Definition of gametophyte noun Botany (in the life cycle of plants with alternating generations) the gamete-producing and usually haploid phase, producing the zygote from which the sporophyte arises. It is the dominant form in bryophytes. Derivatives gametophyticPronunciation: /-ˈfɪtɪk/ adjective gametophyte in other Oxford dictionaries Definition of gametophyte in the US English dictionary