Source : Webster's Revised Unabridged Dictionary (1913)

Hay \Hay\, n. [OE. hei, AS. h?g; akin to D. kooi, OHG. hewi,
   houwi, G. heu, Dan. & Sw. h["o], Icel. hey, ha, Goth. hawi
   grass, fr. the root of E. hew. See {Hew to cut}. ]
   Grass cut and cured for fodder.

         Make hay while the sun shines.           --Camden.

         Hay may be dried too much as well as too little. --C.
                                                  L. Flint.

   {Hay cap}, a canvas covering for a haycock.

   {Hay fever} (Med.), nasal catarrh accompanied with fever, and
      sometimes with paroxysms of dyspn[oe]a, to which some
      persons are subject in the spring and summer seasons. It
      has been attributed to the effluvium from hay, and to the
      pollen of certain plants. It is also called {hay asthma},
      {hay cold}, and {rose fever}.

   {Hay knife}, a sharp instrument used in cutting hay out of a
      stack or mow.

   {Hay press}, a press for baling loose hay.

   {Hay tea}, the juice of hay extracted by boiling, used as
      food for cattle, etc.

   {Hay tedder}, a machine for spreading and turning newmown
      hay. See {Tedder}.

Source : WordNet®

hay fever
     n : a seasonal rhinitis resulting from an allergic reaction to
         pollen [syn: {pollinosis}]