triploidPronunciation: /ˈtrɪplɔɪd/ GeneticsDefinition of triploid adjective (of a cell or nucleus) containing three homologous sets of chromosomes: a triploid endosperm nucleus (of an organism or species) composed of triploid cells: a triploid carp noun a triploid organism, variety, or species: this cross produces many infertile triploidsDerivatives triploidy noun triploid in other Oxford dictionaries Definition of triploid in the US English dictionary