A lili is the offspring of a liger and a lion. Only female ligers are fertile, as according to Haldane's rule, in hybrids of animals whose sex is determined by sex chromosomes, if one is sterile, rare or absent, it is the heterogametic sex (different sex chromosomes) - so for the liger it is the male (XY). This means that a female liger can only mate with a male lion, which produces a lili.