Izaiah is a modern American spelling of Isaiah, the Hebrew Yesha'yahu, which means "Yahweh is salvation" or "God saves". The biblical Isaiah is the prophet whose book is among the most quoted in the Old Testament, and the z spelling gives the name a sharper, more contemporary look. In the United States Izaiah has been in the top 1000 since 2000, peaked at number 390 in 2011 and ranks 635 in 2025.