polyploidy

polyploidia puhekieltä The state or condition of being a polyploid; having more than the usual two homologous sets of chromosomes.
2011, Terence Allen and Graham Cowling, The Cell: A Very Short Introduction, Oxford 2011, p. 90:

As they mature, the DNA is replicated several times but the cell does not divide, a condition known as polyploidy which allows cells to increase in size.