meiosis - cell division necessary for sexual reproduction in eukaryotes, such as animals, plants and fungi. The number of sets of chromosomes in the cell undergoing meiosis is reduced to half the original number, typically from two sets (diploid) to one set (haploid). The cells produced by meiosis are either gametes (the usual case in animals) or otherwise usually spores from which gametes are ultimately produced (the case in land plants).
