The Collaborative International Dictionary of English v.0.48:

Barley \Bar"ley\, n. [OE. barli, barlich, AS. b[ae]rlic; bere
   barley + l[imac]c (which is prob. the same as E. like, adj.,
   or perh. a form of AS. le[=a]c leek). AS. bere is akin to
   Icel, barr barley, Goth. barizeins made of barley, L. far
   spelt; cf. W. barlys barley, bara bread. ?92. Cf. Farina,
   6th Bear.] (Bot.)
   A valuable grain, of the family of grasses, genus Hordeum,
   used for food, and for making malt, from which are prepared
   beer, ale, and whisky.
   [1913 Webster]

   Barley bird (Zool.), the siskin.

   Barley sugar, sugar boiled till it is brittle (formerly
      with a decoction of barley) and candied.

   Barley water, a decoction of barley, used in medicine, as a
      nutritive and demulcent.
      [1913 Webster] Barleybrake

WordNet (r) 3.0 (2006):

barley
    n 1: a grain of barley [syn: barley, barleycorn]
    2: cultivated since prehistoric times; grown for forage and
       grain

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "barley":
   bird seed, bran, cat food, chicken feed, chop, corn, dog food,
   eatage, ensilage, feed, fodder, forage, grain, hay, mash, meal,
   oats, pasturage, pasture, pet food, provender, scratch,
   scratch feed, silage, slops, straw, swill, wheat



Easton's 1897 Bible Dictionary:

Barley
   a grain much cultivated in Egypt (Ex. 9:31) and in Palestine
   (Lev. 27:16; Deut. 8:8). It was usually the food of horses (1
   Kings 4:28). Barley bread was used by the poorer people (Judg.
   7:13; 2 Kings 4:42). Barley of the first crop was ready for the
   harvest by the time of the Passover, in the middle of April
   (Ruth 1:22; 2 Sam. 21:9). Mention is made of barley-meal (Num.
   5:15). Our Lord fed five thousand with "five barley loaves and
   two small fishes" (John 6:9).