scallion(n = noun.plant) allium porrum, leek - plant having a large slender white bulb and flat overlapping dark green leaves; used in cooking; believed derived from the wild Allium ampeloprasum;
scallion, n. [OF. escalone, eschaloingne, L. caepa Ascalonia onion of Ascalon; caepa onion + Ascalonius of Ascalon, fr. Ascalo Ascalon, a town in Palestine. Cf. Shallot.].
A kind of small onion (Allium Ascalonicum), native of Palestine; the eschalot, or shallot. [1913 Webster]
Any onion which does not “bottom out,” but remains with a thick stem like a leek. Amer. Cyc. [1913 Webster]