Source : Webster's Revised Unabridged Dictionary (1913)

Hop \Hop\, n. [OE. hoppe; akin to D. hop, hoppe, OHG. hopfo, G.
   hopfen; cf. LL. hupa, W. hopez, Armor. houpez, and Icel.
   humall, SW. & Dan. humle.]
   1. (Bot.) A climbing plant ({Humulus Lupulus}), having a
      long, twining, annual stalk. It is cultivated for its
      fruit (hops).

   2. The catkin or strobilaceous fruit of the hop, much used in
      brewing to give a bitter taste.

   3. The fruit of the dog-rose. See {Hip}.

   {Hop back}. (Brewing) See under 1st {Back}.

   {Hop clover} (Bot.), a species of yellow clover having heads
      like hops in miniature ({Trifolium agrarium}, and {T.
      procumbens}).

   {Hop flea} (Zo["o]l.), a small flea beetle ({Haltica
      concinna}), very injurious to hops.

   {Hop fly} (Zo["o]l.), an aphid ({Phorodon humuli}), very
      injurious to hop vines.

   {Hop froth fly} (Zo["o]l.), an hemipterous insect
      ({Aphrophora interrupta}), allied to the cockoo spits. It
      often does great damage to hop vines.

   {Hop hornbeam} (Bot.), an American tree of the genus {Ostrya}
      ({O. Virginica}) the American ironwood; also, a European
      species ({O. vulgaris}).

   {Hop moth} (Zo["o]l.), a moth ({Hypena humuli}), which in the
      larval state is very injurious to hop vines.

   {Hop picker}, one who picks hops.

   {Hop pole}, a pole used to support hop vines.

   {Hop tree} (Bot.), a small American tree ({Ptelia
      trifoliata}), having broad, flattened fruit in large
      clusters, sometimes used as a substitute for hops.

   {Hop vine} (Bot.), the climbing vine or stalk of the hop.

Hornbeam \Horn"beam`\, n. [See {Beam}.] (Bot.)
   A tree of the genus {Carpinus} ({C. Americana}), having a
   smooth gray bark and a ridged trunk, the wood being white and
   very hard. It is common along the banks of streams in the
   United States, and is also called {ironwood}. The English
   hornbeam is {C. Betulus}. The American is called also {blue
   beech} and {water beech}.

   {Hop hornbeam}. (Bot.) See under {Hop}.

Source : WordNet®

hop hornbeam
     n : any of several trees resembling hornbeams with fruiting
         clusters resembling hops