Islip Terrace’s population was 5,641 at the 2000 census. It was originally known as Germantown, but World War I brought pressures to change the name of the community. The name was changed to Islip Terrace in 1922, when the post office was established. Local sources say the name came from the fact that the community was north of, or above, East Islip, and because a terrace connotes a strip of land planted with trees and shrubs.