al·ter·na·tion of generations .ȯl-tər-'nā-shənalso .al- n the occurrence of two or more forms differently produced in the life cycle of a plant or animal usu. involving the regular alternation of a sexual with an asexual generation but not infrequently consisting of alternation of a dioecious generation with one or more parthenogenetic generations
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the regular alternation of two or more different forms or of different modes of reproduction in the life cycle; it may be used specifically for the alternating formation of diploid and haploid generations.Medical dictionary. 2011.