Source : Webster's Revised Unabridged Dictionary (1913)

Regret \Re*gret"\, v. t. [imp. & p. p. {Regretted} (-t[e^]d); p.
   pr. & vb. n. {Regretting}.] [F. regretter, OF. regreter; L.
   pref. re- re- + a word of Teutonic origin; cf. Goth.
   gr[=e]tan to weep, Icel. gr[=a]ta. See {Greet} to lament.]
   To experience regret on account of; to lose or miss with a
   sense of regret; to feel sorrow or dissatisfaction on account
   of (the happening or the loss of something); as, to regret an
   error; to regret lost opportunities or friends.

         Calmly he looked on either life, and here Saw nothing
         to regret, or there to fear.             --Pope.

         In a few hours they [the Israelites] began to regret
         their slavery, and to murmur against their leader.
                                                  --Macaulay.

         Recruits who regretted the plow from which they had
         been violently taken.                    --Macaulay.

Regret \Re*gret"\ (r?*gr?t"), n. [F., fr. regretter. See
   {Regret}, v.]
   1. Pain of mind on account of something done or experienced
      in the past, with a wish that it had been different; a
      looking back with dissatisfaction or with longing; grief;
      sorrow; especially, a mourning on account of the loss of
      some joy, advantage, or satisfaction. ``A passionate
      regret at sin.'' --Dr. H. More.

            What man does not remember with regret the first
            time he read Robinson Crusoe?         --Macaulay.

            Never any prince expressed a more lively regret for
            the loss of a servant. --Clarendon.

            From its peaceful bosom [the grave] spring none but
            fond regrets and tender recollections. --W. Irving.

   2. Dislike; aversion. [Obs.] --Dr. H. More.

   Syn: Grief; concern; sorrow; lamentation; repentance;
        penitence; self-condemnation.

   Usage: {Regret}, {Remorse}, {Compunction}, {Contrition},
          {Repentance}. Regret does not carry with it the energy
          of remorse, the sting of compunction, the sacredness
          of contrition, or the practical character of
          repentance. We even apply the term regret to
          circumstance over which we have had no control, as the
          absence of friends or their loss. When connected with
          ourselves, it relates rather to unwise acts than to
          wrong or sinful ones. --C. J. Smith.

Source : WordNet®

regret
     v 1: feel remorse for; feel sorry for; be contrite about [syn: {repent},
           {rue}]
     2: feel sad about the loss or absence of
     3: decline formally or politely; "I regret I can't come to the
        party"
     4: be sorry; "I regret to say that you did not gain admission
        to Harvard"
     [also: {regretting}, {regretted}]

regret
     n : sadness associated with some wrong done or some
         disappointment; "he drank to drown his sorrows"; "he
         wrote a note expressing his regret"; "to his rue, the
         error cost him the game" [syn: {sorrow}, {rue}, {ruefulness}]
     [also: {regretting}, {regretted}]