Source : Webster's Revised Unabridged Dictionary (1913)

Leek \Leek\ (l[=e]k), n. [AS. le['a]c; akin to D. look, G.
   lauch, OHG. louh, Icel. laukr, Sw. l["o]k, Dan l["o]g. Cf.
   {Garlic}.] (Bot.)
   A plant of the genus {Allium} ({A. Porrum}), having broadly
   linear succulent leaves rising from a loose oblong
   cylindrical bulb. The flavor is stronger than that of the
   common onion.

   {Wild leek}, in America, a plant ({Allium tricoccum}) with a
      cluster of ovoid bulbs and large oblong elliptical leaves.

Source : WordNet®

leek
     n 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: {scallion}, {Allium
          porrum}]
     2: related to onions; white cylindrical bulb and flat
        dark-green leaves