Borrowed from Indonesian Sumatera, from Sanskrit समुद्र (samudra, “sea”). Mentioned in the 11th century in Sanskrit as समुद्रभूमि (samudrabhūmi, “land of Sumatra”), gradually replacing the earlier सुवर्णद्वीप (suvarṇadvīpa).
Practice speaking and memorizing "Sumatra" and many other words and sentences in English.