Source : Webster's Revised Unabridged Dictionary (1913)

Bitter \Bit"ter\, n. [See {Bitts}.] (Naut.)
   AA turn of the cable which is round the bitts.

   {Bitter end}, that part of a cable which is abaft the bitts,
      and so within board, when the ship rides at anchor.

Bitter \Bit"ter\, a. [AS. biter; akin to Goth. baitrs, Icel.
   bitr, Dan., Sw., D., & G. bitter, OS. bittar, fr. root of E.
   bite. See {Bite}, v. t.]
   1. Having a peculiar, acrid, biting taste, like that of
      wormwood or an infusion of hops; as, a bitter medicine;
      bitter as aloes.

   2. Causing pain or smart; piercing; painful; sharp; severe;
      as, a bitter cold day.

   3. Causing, or fitted to cause, pain or distress to the mind;
      calamitous; poignant.

            It is an evil thing and bitter, that thou hast
            forsaken the Lord thy God.            --Jer. ii. 19.

   4. Characterized by sharpness, severity, or cruelty; harsh;
      stern; virulent; as, bitter reproach.

            Husbands, love your wives, and be not bitter against
            them.                                 --Col. iii.
                                                  19.

   5. Mournful; sad; distressing; painful; pitiable.

            The Egyptians . . . made their lives bitter with
            hard bondage.                         --Ex. i. 14.

   {Bitter apple}, {Bitter cucumber}, {Bitter gourd}. (Bot.) See
      {Colocynth}.

   {Bitter cress} (Bot.), a plant of the genus {Cardamine}, esp.
      {C. amara}.

   {Bitter earth} (Min.), tale earth; calcined magnesia.

   {Bitter principles} (Chem.), a class of substances, extracted
      from vegetable products, having strong bitter taste but
      with no sharply defined chemical characteristics.

   {Bitter salt}, Epsom salts; magnesium sulphate.

   {Bitter vetch} (Bot.), a name given to two European
      leguminous herbs, {Vicia Orobus} and {Ervum Ervilia}.

   {To the bitter end}, to the last extremity, however
      calamitous.

   Syn: Acrid; sharp; harsh; pungent; stinging; cutting; severe;
        acrimonious.

Bitter \Bit"ter\, n.
   Any substance that is bitter. See {Bitters}.

Bitter \Bit"ter\, v. t.
   To make bitter. --Wolcott.

Source : WordNet®

bitter
     adj 1: marked by strong resentment or cynicism; "an acrimonious
            dispute"; "bitter about the divorce" [syn: {acrimonious}]
     2: very difficult to accept or bear; "the bitter truth"; "a
        bitter sorrow"
     3: harsh or corrosive in tone; "an acerbic tone piercing
        otherwise flowery prose"; "a barrage of acid comments";
        "her acrid remarks make her many enemies"; "bitter words";
        "blistering criticism"; "caustic jokes about political
        assassination, talk-show hosts and medical ethics"; "a
        sulfurous denunciation" [syn: {acerb}, {acerbic}, {acid},
        {acrid}, {blistering}, {caustic}, {sulfurous}, {sulphurous},
         {venomous}, {virulent}, {vitriolic}]
     4: one of the four basic taste sensations; sharp and
        disagreeable; like the taste of quinine
     5: expressive of severe grief or regret; "shed bitter tears"
     6: proceeding from or exhibiting great hostility or animosity;
        "a bitter struggle"; "bitter enemies"
     7: causing a sharply painful or stinging sensation; used
        especially of cold; "bitter cold"; "a biting wind" [syn: {biting}]

bitter
     n 1: English term for a dry sharp-tasting ale with strong flavor
          of hops (usually on draft)
     2: the taste experience when quinine or coffee is taken into
        the mouth [syn: {bitterness}]
     3: the property of having a harsh unpleasant taste [syn: {bitterness}]

bitter
     adv : extremely and sharply; "it was bitterly cold"; "bitter cold"
           [syn: {piercingly}, {bitterly}, {bitingly}]

bitter
     v : make bitter