The term for a type of cell division that reduces the chromosome number by half is meiosis. This specialized process is essential for the formation of gametes, such as sperm and egg cells, during sexual reproduction. Meiosis consists of two consecutive divisions, meiosis I and meiosis II, which results in four haploid cells from a single diploid cell. This reduction ensures that upon fertilization, the resulting zygote will have the correct diploid number of chromosomes, maintaining genetic stability across generations.