Source : Webster's Revised Unabridged Dictionary (1913)

Lentil \Len"til\ (l[e^]n"t[i^]l), n. [F. lentille, fr. L.
   lenticula, dim. of lens, lentis, lentil. Cf. {Lens}.] (Bot.)
   A leguminous plant of the genus {Ervum} ({Ervum Lens}), of
   small size, common in the fields in Europe. Also, its seed,
   which is used for food on the continent.

   Note: The lentil of the Scriptures probably included several
         other vetchlike plants.

   {Lentil shell} (Zo["o]l.), a small bivalve shell of the genus
      {Ervillia}, family {Tellinid[ae]}.

Source : WordNet®

lentil
     n 1: round flat seed of the lentil plant
     2: the fruit or seed of a lentil plant
     3: widely cultivated Eurasian annual herb grown for its edible
        flattened seeds that are cooked like peas and also ground
        into meal and for its leafy stalks that are used as fodder
        [syn: {lentil plant}, {Lens culinaris}]