Source : Webster's Revised Unabridged Dictionary (1913)

Assay \As*say"\, v. t. [imp. & p. p. {Assayed}; p. pr. & vb. n.
   {Assaying}.] [OF. asaier, essaier, F. essayer, fr. essai. See
   {Assay}, n., {Essay}, v.]
   1. To try; to attempt; to apply. [Obs. or Archaic]

            To-night let us assay our plot.       --Shak.

            Soft words to his fierce passion she assayed.
                                                  --Milton.

   2. To affect. [Obs.]

            When the heart is ill assayed.        --Spenser.

   3. To try tasting, as food or drink. [Obs.]

   4. To subject, as an ore, alloy, or other metallic compound,
      to chemical or metallurgical examination, in order to
      determine the amount of a particular metal contained in
      it, or to ascertain its composition.

Assay \As*say"\, n. [OF. asai, essai, trial, F. essa. See
   {Essay}, n.]
   1. Trial; attempt; essay. [Obs.] --Chaucer.

            I am withal persuaded that it may prove much more
            easy in the assay than it now seems at distance.
                                                  --Milton.

   2. Examination and determination; test; as, an assay of bread
      or wine. [Obs.]

            This can not be, by no assay of reason. --Shak.

   3. Trial by danger or by affliction; adventure; risk;
      hardship; state of being tried. [Obs.]

            Through many hard assays which did betide.
                                                  --Spenser.

   4. Tested purity or value. [Obs.]

            With gold and pearl of rich assay.    --Spenser.

   5. (Metallurgy) The act or process of ascertaining the
      proportion of a particular metal in an ore or alloy;
      especially, the determination of the proportion of gold or
      silver in bullion or coin.

   6. The alloy or metal to be assayed. --Ure.

   Usage: {Assay} and {essay} are radically the same word; but
          modern usage has appropriated {assay} chiefly to
          experiments in metallurgy, and {essay} to intellectual
          and bodily efforts. See {Essay}.

   Note: Assay is used adjectively or as the first part of a
         compound; as, assay balance, assay furnace.

   {Assay master}, an officer who assays or tests gold or silver
      coin or bullion.

   {Assay ton}, a weight of 29,1662/3 grams.

Assay \As*say"\, v. i.
   To attempt, try, or endeavor. [Archaic. In this sense essay
   is now commonly used.]

         She thrice assayed to speak.             --Dryden.

Source : WordNet®

assay
     n 1: an appraisal of the state of affairs; "they made an assay of
          the contents"; "a check on its dependability under
          stress" [syn: {check}]
     2: a substance that is undergoing an analysis of its components
     3: a written report of the results of an analysis of the
        composition of some substance
     4: a quantitative or qualitative test of a substance
        (especially an ore or a drug) to determine its components;
        frequently used to test for the presence or concentration
        of infectious agents or antibodies etc.
     v 1: analyze (chemical substances)
     2: make an effort or attempt; "He tried to shake off his
        fears"; "The infant had essayed a few wobbly steps"; "The
        police attempted to stop the thief"; "He sought to improve
        himself"; "She always seeks to do good in the world" [syn:
         {try}, {seek}, {attempt}, {essay}]