se·rot·i·nal \sə̇ˈrätənəl, seˈr-; |serə|tīnəl\adjective Etymology: Latin serotinus coming late + English -al — more at serotine : of or relating to the latter and usually drier part of summer : occurring in the latter half of summer < a serotinal generation of aphids > < ponds … drying up about the beginning of the serotinal season — Ecology >