1. plant having a large slender white bulb and flat overlapping dark green leaves; used in cooking; believed derived from the wild Allium ampeloprasum • Syn: leek, Allium porrum • Hypernyms: alliaceous plant • Part Meronyms: leek 2. a young onion before the bulb has enlarged; eaten in salads • Syn: green onion, spring onion • Regions: United States, Britain (for: spring onion) • Hypernyms: onion