Scallion, green onion, and spring onion are English names (with many other regional names throughout the world) for various Allium species. All of the Allium have hollow green leaves (like the common onion), but these are used while they lack a fully developed root bulb. Used as a vegetable, they are eaten either raw or cooked. Scallions have a milder taste than most onions.
The words scallion and shallot are related and can be traced back to the Greek ασκολόνιον ('askolonion') as described by the Greek writer Theophrastus. This name, in turn, seems to originate from the name of the town of Ashkelon. The plant itself apparently came from farther east of Europe.
Species and cultivars which may be called "scallions" include: