scallion means: A scallion, which is actually a green onions, is an immature green onion that has a white base and green leaves. Both the leaves and base of the scallion can be eaten. (in Cooking Dictionary)

What else does scallion mean?

An onion bunch or young onion that has been harvested before the bulb grows. (in Merlin Dictionary)

One of many onion-like plants such as the shallot. (in Merlin Dictionary)