Simplify the following text for a Grade 7 native English-speaking person.
Original: The etymology of the common name Emu is uncertain , but is thought to have come from an Arabic word for large bird that was later used by Portuguese explorers to describe the related Cassowary in Australia and New Guinea .
Simplified: The history of the common name , Emu , is not certain , but is thought to have come from an Arabic word for large bird . This word was later used by Portuguese explorers to describe the related Cassowary in New Guinea .