Isai is a ♂ male name.
The name Isai is an e.g. German cognate of the biblical name Jesse, which is of Hebrew origin. In the Old Testament, Isai is the father of King David.
Isai means “gift of God” (from Hebrew “shay/שַׁי” = present/gift), but as well “God exists” (from Hebrew “yésh/יֵשׁ” = there is/there exist).